--- title: "Designed with respect for children" description: "How the rules on selling to children shaped Professor Oops: no ads, nothing locked in play, a grown-ups’ sum, three polite asks and very little data." source_name: "Game Tailors" source_url: "https://professoroops.com/en/inside/research-respect/" site_home: "https://professoroops.com/" source_description: "The drawing app where the paper is real. No ads. No accounts. No personal data: only anonymous counts, which you can switch off." locale: "en" legal: - "Game Tailors · Schieweg 15Y-40, 2627 AN Delft (NL)" - "KvK 92437702 · VAT NL866044474B01" - "info@gametailors.com · +31 6 4227 5919" copyright: "© 2026 Game Tailors" published_at: "2026-11-10T12:03:07.472Z" modified_at: "2026-11-10T12:03:07.472Z" --- # Designed with respect for children ## We read the rules on selling to children, then built to them Before the shop was built, we read what regulators, app stores and child researchers say about games and money. Almost all of it points one way. So Professor Oops has no ads, nothing locked or priced in play, one purchase for grown-ups behind a sum, at most three polite asks, and very little data sent. Where we chose to be softer than the strictest reading, this page says so. [For engineers](<#hood-engineers>) ![Painted illustration of a wooden toolbox tied with a red ribbon next to a single coin on a yellow sheet with a ketchup zigzag, the painter reading a book beside it.]() ## In play, a child meets no locks, no prices and no pictures of what's for sale A child who opens Professor Oops finds tabs full of tools that work. The free version has whole tabs $the kitchen, the science kit, the toolbox$, the drawing tools, and a few more things such as water and the sponge. A tab that would otherwise have nothing free gets one "taster" that says what the tab is about: the face plant in the toy box, the ants in the garden. Nothing is greyed out. Nothing has a padlock. No character says "ask your parents". That isn't an accident of style. European law lists, among practices that are always unfair, a direct appeal to children in an advert to buy something or to get an adult to buy it for them ^{[EU 2005]()}. The UK's games principles give examples of what is unlikely to comply, such as an unhappy cartoon character used to push a purchase ^{[OFT 2014]()}. The US Federal Trade Commission names "parasocial relationship pressure", a loved character used to sell ^{[FTC 2022]()}. Researchers who coded 133 apps played by 160 children aged 3 to 5 found that about four in five used at least one manipulative design: lures, time pressure, a character asking for money. One app said "You can play with these cute animals for a tiny fee\! Ask your parents\!" ^{[Radesky 2022]()}. We built to the other side of that line. In play we do show one thing, and we want to be clear about it. At the end of a tab with more in the full version, there is a small paper tile with reading glasses and a number, like "\+12". It has no tool pictures, no words, no price and no padlock. It never moves, glows or makes a sound. Tapping it opens the grown-ups' sum. The strictest reading of the research said to show no sign of the paid tools at all. We decided a quiet door for grown-ups is fair, and we put it on the ladder below where it belongs. We read the rules on selling to children, then built to them For engineers ### We read the rules on selling to children, then built to them No ad or analytics SDK $runtime dependencies are Capacitor plugins and the store purchase, plus one partner SDK in the Android app$. Android's advertising-ID permission is stripped, and an automated test holds the permission list. Asks have a fixed budget: three in all, at least seven days apart, and a permanent "never". The gate's sum comes from 252 possible pairs, with three tries. Anonymous daily totals carry no identifier and no time finer than a day, and start switched off in 32 country codes and wherever the country is unknown. [Under the hood](<#hood-play-space>) In play, a child meets no locks, no prices and no pictures of what's for sale Under the hood ### In play, a child meets no locks, no prices and no pictures of what's for sale The split between free and full is plain data, kept apart from the tools themselves: the free tabs, the drawing tools, a few free things elsewhere, and one taster for each tab that would otherwise have nothing free $the face in the toy box, the ants in the garden$, so no tab is ever empty. The ants are also the welcome gift. The tile's accessible name is the grown-ups' button's own $"Parents & teachers"$, never "12 more tools", so a screen reader doesn't advertise to a child either. A tap opens the gate first, then the grown-ups' area at that tab's part, and never the purchase itself. Automated tests pin it: the tile has no painter, never moves and always puts the gate first; every tab is there, and where the rest of a tab is paid, the taster is its one free tool. The ladder of teasing, and where the game stands on it - **0 · Nothing paid is visible to the child.** Every tool in play works. No sign of what isn't there. *Professor Oops: the tools themselves.* - **1 · A neutral door for grown-ups.** A "for grown-ups" button, a store page, a tour that an adult opens. *Professor Oops: the grown-ups' button and tour.* - **2 · A neutral display in the child's space.** Paid tools shown greyed out, with no lock, no words, no character. Legal risk low to medium; it exists to create wanting. *Arguably between 1 and 2: the static "\+N" tile.* - **3 · Locks, or "ask a grown-up".** Padlocks on tools, "Ask a grown-up to unlock\!". That is literally asking a child to persuade an adult to buy. *Not in the game.* - **4 · A locked present or an emotional lure.** A wrapped box that waits for payment, a sad animal, "it disappears if…". *Not in the game.* The five levels are from our own research notes on monetisation, written before the shop was built; the legal risks are their reading of EU point 28 ^{[EU 2005]()}, OFT principles 4 and 6 ^{[OFT 2014]()}, the CPC principles ^{[CPC 2025]()} and ACM practice ^{[ACM 2024]()}. ![The end of the Garden tab in the free game: the ants, then a small paper tile with reading glasses and a number.]() **The one sign of more, in the game itself.** The Garden tab of the free version: the ants, then the grown-ups' "\+N" tile. No pictures of the tools, no words, no price, and a tap opens the sum. ### The research changed the shop before it was built Our first ideas for selling the full version were warm ones. They were also, it turned out, the very patterns the research warns about. Here is what each one became. First idea · Dropped ### A locked present the child can see, opened when a parent pays Pester power by design: point 28, "persuade adults to buy it for them" ^{[CPC 2025]()}, and the "just ask your parents" pattern ^{[Radesky 2022]()}. A gate in front doesn't cure it. **Built instead:** A welcome gift for every family, the ants, with no condition and no announcement. It arrives on the second launch. First idea · Dropped ### If the parent says no, the present is gone A one-chance offer is scarcity aimed at a purchase, the kind of pressure the Dutch regulator fined ^{[ACM 2024]()}. And the child would see the loss. **Built instead:** Nothing given is ever taken away. No trial expires. First idea · Dropped ### A new present every day for families who haven't paid "Come back tomorrow" was coded as manipulative ^{[Radesky 2022]()}; it is a streak in all but name. **Built instead:** "One tool a day" exists only after buying, as a grown-up's choice. A missed day just means the next tool comes later. First idea · Dropped ### Sell single tools cheaply beside the whole toolbox Many small products multiply the moments to buy, and children want specific animals, so each one invites its own pestering. **Built instead:** One product: the full toolbox. First idea · Kept, with limits ### Ask the parent again now and then, nicely A request with no permanent "no" is nagging ^{[FTC 2022]()}. **Built instead:** Three asks in all, a week apart, each with "No thanks, don't ask again". Most young children’s apps had pressure or ads in them 107 of 133 apps had a manipulative design coded and 26 had none; 129 of 135 had advertising and 6 had none. - had it - had none Data table Most young children’s apps had pressure or ads in them | | had it | had none | | --- | --- | --- | | Pressure designs | 107 | 26 | | Advertising | 129 | 6 | Source: Published counts: 26 of 133 apps with no manipulative design coded ^{[Radesky 2022]()}; 129 of 135 apps with at least one kind of advertising ^{[Meyer 2019]()}. Studies of other apps, not of Professor Oops. ## Grown-ups' settings sit behind an addition that stops a five-year-old but not an older child Anything a grown-up must decide sits behind a short addition: the grown-ups' area, the offer and its price, paying, and a link out of the app. Apple asks kids' apps for "adult-level tasks" in front of such things ^{[Apple Kids]()}. The sum is a two-digit number plus a round ten, never more than 100, like 37 \+ 40. A wrong answer brings a new sum, so the answer can't be found by trying. Three wrong answers close it, and the child is back at play with nothing lost. Our research asked for something harder, a task a ten-year-old couldn't solve casually. We started with a multiplication, then an addition with a carry, and found both too hard for a quick grown-up step. So we made it easier, twice, on purpose. It is a real hurdle for a five-year-old. We expect it won't stop many eight- to ten-year-olds, and we don't pretend it does. We also looked for a controlled study showing that parental gates work at all, and found none. So we rely on what's behind it: no urgency, no countdown, and the store's own payment sheet after the offer. In the next update a grown-up can switch the sum off for the area, the tour, saving a picture in the apps and redeeming a code next update. Paying and a way out of the app still ask unless a grown-up has just solved the sum, and more play time always asks, so a child can never give themselves more time. [Under the hood](<#hood-gate>) Grown-ups' settings sit behind an addition that stops a five-year-old but not an older child Under the hood ### Grown-ups' settings sit behind an addition that stops a five-year-old but not an older child The first number has two digits and never ends in 0. The second is a round ten from 20 up, chosen so the total stays at 100 or under. Every first number that leaves room for a ten is equally likely, and so is every ten that fits. That gives 252 possible pairs, with answers from 31 to 99, and no answer ends in 0. two digits, not ending in 0 · plus a round ten from 20 · total ≤ 100 · three tries The answer must match the total exactly. After a wrong answer the gate shows a different sum, and the third wrong answer closes it. The sums come from a seeded random sequence, so the same seed always gives the same sums and the tests can repeat a session exactly. next update Each reason for the sum follows its own rule. More play time always asks. The area, the tour, saving a picture and redeeming a code follow the grown-up's switch. A link out asks only in the apps. Paying and a link out skip the sum only if the way in was a solved sum, never past a switched-off one. Try it: pass the grown-ups' sum The game's own ruleThe sum is drawn by the game's own rule, and checked with three tries as in the game: a wrong answer brings a new sum. It types answers by itself until you tap the keys, or use the buttons. **What to look for:** how fast a grown-up gets through, and that a wrong answer costs a try but never a scolding. Three wrong and the door closes, back to play. ![The grown-ups’ sum: two numbers to add, a keypad and three tries]() - FOR GROWN-UPS - 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 0 - ⌫ - OK - a grown-up is typing… - tap the keys - ✓ Open - the grown-ups’ area - Closed: back to play - nothing lost, no message - Not quite: a new sum. sum— plus— tries left— gates opened— possible sums— ![The grown-ups' sum screen in the game: a two-digit number plus a round ten, an answer field and a keypad.]() **The real gate.** A two-digit number plus a round ten. Quick for a grown-up, a real hurdle for a five-year-old. The gate’s answers spread from 31 to 99, so a guess rarely worksThe likeliest single answer comes up 4.1% of the time, and each wrong answer brings a new sum, so three blind guesses would pass about 12% of the time; a child who can add passes every time. The 252 sums give answers from 31 to 99; the likeliest, 91, comes up 4.1 % of the time. Data table The gate’s answers spread from 31 to 99, so a guess rarely works | the answer $a \+ b$ | chance of each answer | | --- | --- | | 31 | 0.23% | | 32 | 0.23% | | 33 | 0.23% | | 34 | 0.23% | | 35 | 0.23% | | 36 | 0.23% | | 37 | 0.23% | | 38 | 0.23% | | 39 | 0.23% | | 41 | 0.49% | | 42 | 0.49% | | 43 | 0.49% | | 44 | 0.49% | | 45 | 0.49% | | 46 | 0.49% | | 47 | 0.49% | | 48 | 0.49% | | 49 | 0.49% | | 51 | 0.81% | | 52 | 0.81% | | 53 | 0.81% | | 54 | 0.81% | | 55 | 0.81% | | 56 | 0.81% | | 57 | 0.81% | | 58 | 0.81% | | 59 | 0.81% | | 61 | 1.21% | | 62 | 1.21% | | 63 | 1.21% | | 64 | 1.21% | | 65 | 1.21% | | 66 | 1.21% | | 67 | 1.21% | | 68 | 1.21% | | 69 | 1.21% | | 71 | 1.73% | | 72 | 1.73% | | 73 | 1.73% | | 74 | 1.73% | | 75 | 1.73% | | 76 | 1.73% | | 77 | 1.73% | | 78 | 1.73% | | 79 | 1.73% | | 81 | 2.53% | | 82 | 2.53% | | 83 | 2.53% | | 84 | 2.53% | | 85 | 2.53% | | 86 | 2.53% | | 87 | 2.53% | | 88 | 2.53% | | 89 | 2.53% | | 91 | 4.12% | | 92 | 4.12% | | 93 | 4.12% | | 94 | 4.12% | | 95 | 4.12% | | 96 | 4.12% | | 97 | 4.12% | | 98 | 4.12% | | 99 | 4.12% | Source: Computed exactly from the game’s own rule: 252 possible pairs, the first number uniform over its 63 values, the round ten uniform over those that keep the total within 100. No answer ever ends in 0. ## The game asks a grown-up at most three times, a week apart, and no means no The game may mention the full version to a grown-up again, but rarely. There are three asks in all. Each one waits at least seven days after the last. Every ask has a plain "No thanks, don't ask again", and after that the game never asks again: the tiles go too, and the start screen simply says "Free version". Only a grown-up can turn the reminders back on, in the settings, and then they come no more often and no more times than before. A family that owns the full version is never asked. A clock set backwards unlocks nothing. The offer itself has one bold button with the price in it, and "Not now" sits right under it in readable text, never as grey small print. There is no timer, no "only today" and no countdown. The Dutch regulator fined a big game maker €1,125,000 over "buy now" pressure on children and misleading countdowns ^{[ACM 2024]()}. The first-launch welcome shows no price at all, as Google Play's Families policy asks ^{[Google Families]()}. Here is a seam we want to show. Our research said "never at launch". From the third launch, though, the start screen's grown-ups' strip can open into a short reminder in words, without a sum first. It shows no price and no tool pictures, and it spends one of the same three asks. It is on a screen a child can see, which is why it holds to the budget. [Under the hood](<#hood-asks>) The game asks a grown-up at most three times, a week apart, and no means no Under the hood ### The game asks a grown-up at most three times, a week apart, and no means no One budget is shared by the strip's reminder and the "by the way" card in the grown-ups' area, so the two together never ask more than three times. An ask may come only when all of these hold: the family doesn't own the full version, no grown-up has said "don't ask again", fewer than three asks have been made, and a full week has passed since the last one. The strip's reminder adds a few more: the family can buy where it is, no payment is on its way, it is at least the third launch, and the strip isn't still offering the tour, so only one thing is offered at a time. Automated tests pin each of these, including a clock set backwards. Try it: twelve weeks of a family's launches The game's own ruleEach dot is a day the game is opened. Above the line: **W** the welcome $no price$, **G** the welcome gift, **T** the strip offering the tour, and flags **1**, **2**, **3** for each reminder, which is an ask. The shaded weeks are when no ask may come, and pale marks are still to come. Change how often the game is opened, whether a grown-up watched the tour, and what they tap. **What to look for:** however often a child plays, there are never more than three asks, and "don't ask again" ends them for good. Shaded: the week after an ask. Grey dots: after "don't ask again". ![Twelve weeks of launches with the welcome, the gift, the tour and at most three reminders marked]() - wk 1 - wk 2 - wk 3 - wk 4 - wk 5 - wk 6 - wk 7 - wk 8 - wk 9 - wk 10 - wk 11 - wk 12 - W - G - T - T - T - 1 - 2 - 3 - "don’t ask again": no more, ever Days between launches2 days Each time, the grown-up tapsNot nowNo thanks, don’t ask again day— launches— asks used— next ask— launches in 12 weeks— ![The start screen's grown-ups' strip: reading glasses, Parents & teachers, and the words Free version.]() **The start screen's grown-ups' strip, after "don't ask again".** Just "Free version": words for a grown-up, with no price and no tool pictures. Before that it also says how many more things the full toolbox has, and when it opens into a reminder, that spends one of the three asks. ### A break waits for the stroke to finish A grown-up can set a daily play limit of 15, 30 or 45 minutes or an hour. It is off unless they choose it. Two minutes before the end, the painter says so once. At the end the game rests behind "Time for a break\!", never in the middle of a stroke, with the drawing saved. Adding 15 minutes for today always needs the sum. There are no streaks and no rewards for coming back. The limit exists because Brazil's new law asks for parental time tools ^{[Brazil 2025]()}, and we give it to every family for free. One study we found later raises a fair question about our two-minute warning. Parents of children aged 1 to 5 reported that their own two-minute warnings made transitions worse, while transitions the technology ended went better ^{[Hiniker 2016]()}. Ours comes from the device, which the authors proposed as a possible fix without testing it, and our players are mostly older. We keep it, and we keep watching that question. [Under the hood](<#hood-break>) A break waits for the stroke to finish Under the hood ### A break waits for the stroke to finish ![The Time for a break\! screen at the end of the daily play limit: the painter, the words Your drawing is kept. See you next time\!, and a small Parents & teachers: 15 more minutes button.]() **"Time for a break\!"** The drawing is kept, and more time is a grown-up's button. No streak, no reward for coming back tomorrow. The limit is off, 15, 30 or 45 minutes, or an hour; the warning comes two minutes before the end, and "more time" adds 15 minutes. Only time with the game in front counts, and a device that slept doesn't eat the day. The count starts again at local midnight and is kept on the device only. An automated test checks it. ## One purchase, with no coins, no surprises and nothing taken back There is one thing to buy: the full toolbox. No subscription, no virtual coins, no gems, no random boxes. Paid random content is a loot box, and Brazil's 2025 law bans those in games children are likely to play ^{[Brazil 2025]()}. The toolbox is a fixed, listed set, so there is nothing to gamble on. A grown-up who buys it chooses how it arrives: everything at once, wrapped as a present to open later, or one new tool a day. Any switch can only bring more, and nothing given is ever taken away. Buying on the web comes with a "Withdraw from purchase" button for 14 days. Where the store country is Ukraine, the full version is free. "One price" means one product, not one number everywhere. The web price is €5.99, lower in Spain, Italy and Greece $€4.99$ and Portugal $€3.99$, and the app stores use their own local prices. The flow is always the same: the sum, an offer with the price on it, then the store's own sheet. The US case against a big game maker, settled for $275 million plus $245 million in refunds, shaped that order ^{[FTC 2022b]()}. [Under the hood](<#hood-price>) One purchase, with no coins, no surprises and nothing taken back Under the hood ### One purchase, with no coins, no surprises and nothing taken back Delivery is a small set of rules with no side effects. A switch may only go towards more, sooner: - **A wrapped present may become** everything now, or one a day. - **One a day may become** everything now. - **Everything now stays** everything now. "One a day" gives one tool per new local date, however many days were skipped, and a date not later than the last changes nothing, so a clock set backwards gains nothing. The welcome gift comes with a new session at least 20 minutes after the first launch. The Ukraine rule reads the country of the store account. The withdrawal button stays for 14 days. Automated tests pin delivery, withdrawal and the store country. ## What leaves the device is a few totals, and a grown-up can switch them off Professor Oops has no accounts, and the game asks for no name, e-mail address or birthday. $A grown-up who buys in the browser gives the payment page an e-mail address for the receipt.$ It carries no advertising code and no analytics library from another company. One study of 5,855 popular free children's Android apps found a majority potentially breaking the US children's privacy rule, mostly through such third-party libraries ^{[Reyes 2018]()}. We read that later, and it fits the choice we had already made. On Android, the advertising-ID permission that a library could slip in is removed, and a test holds the list of permissions. On iOS the app declares no tracking. The Android app does carry one partner library, which unlocks the full version on a partner's children's tablets. The released game uses neither the microphone nor the camera. We do count a little, ourselves. Once a day at most, the game can send a short report of what was used: which tools, how many times, in which language. It has no identifier, no time finer than a day and no free text. The server adds it to daily totals and keeps nothing else from it. Off stores nothing, and switching off deletes the device's record. Where we read the law as asking for consent first, the counts start switched off: the UK, most of the EU and EEA, and anywhere the country can't be told. We read Dutch, French and Italian rules as exempting this kind of first-party counting, so there they start switched on, like the rest of the world. A grown-up's choice in the settings always wins, and an update never resets it. Like any website, the server sees an internet address with each request, and our hosting provider keeps its own records. That is why we say "anonymous counts" and not "no data". [Under the hood](<#hood-privacy>) What leaves the device is a few totals, and a grown-up can switch them off Under the hood ### What leaves the device is a few totals, and a grown-up can switch them off The report holds coarse buckets $how long counting has run, days since last played, launches$ instead of exact numbers, and only names from the game's own list of tools, so there is no free text to leak. Before the first report, the web game asks the server whether counting starts on where it is; the server answers from the request's country and keeps nothing. Requests carry no cookies. The device's record lives at most 395 days; daily totals are kept 25 months, then folded into monthly ones. The apps send no country. Automated tests check the report's shape and what the server keeps. Why off by default in most of Europe: the ePrivacy rule covers information read from a device, personal or not, and our reading of the European Data Protection Board's guidelines on its scope is that sending counts made on the device falls under it ^{[EDPB 2024]()}. The privacy page has a "For children" box in plain words, as the GDPR asks ^{[GDPR 2016]()}. Stays on the device ### The child's world - Every drawing and saved picture - The play-time limit and today's minutes - The asks record and the gift - The counting's own record: first day, last day, launches $only coarse buckets of it ever leave$ Sent at most once a day, if switched on ### One report, in plain words - Which app $web, Android or iOS$, its version and its language - Free or full version - Coarse buckets: how long counting has run, days since last played, launches - Which tools were used and how often, such as the crayon 14 times and ketchup twice - Which colouring pages were opened - No identifier, no time finer than a day, no free text What the server keeps from it ### One more in a few day totals - A count per day for each thing counted, and nothing else - One more report from the web, one more in Dutch, one more second launch - Crayon \+14, ketchup \+2, the cat-in-the-window page \+1 - The country \+1, on the web only, as a total of its own that is split by nothing Where counting starts switched off GB, GG, JE, IM, AT, BE, BG, HR, CY, CZ, DK, EE, FI, DE, GR, HU, IE, LV, LT, LU, MT, PL, PT, RO, SK, SI, ES, SE, AX, IS, LI, NO, and unknown. **Starts on, with a national exemption for first-party counts:** NL, FR, IT, and every country not listed. ## Safety lines say what happens, then what a grown-up does The game lets a child do things they mustn't do at home: pour water on burning oil, mix bleach with vinegar, clip a battery to steel wool. When they do, the painter says what really happens and what to do instead, calmly and once. The burning-oil line comes back at most once a minute. No line scolds. The fire buttons follow the same idea. During a pan fire the game offers "Put a lid on" and has no water button. Water thrown on burning oil flares up, and flour flares up too. Fire guidance we read later says the same about the lid, turning off the heat and never using water ^{[NFPA 2026](), [Brandweer NL]()}, and health guidance agrees with the bleach line: mixing makes chlorine gas, so get to fresh air ^{[Chang 2020]()}. There is a second fire button, "Damp tea towel", and here the advice is not settled. A UK fire service now warns never to throw water or a damp tea towel over a pan fire ^{[Essex 2024]()}, and the American and Dutch guidance we read gives no towel for a pan fire. We'd rather show that here than leave it out. And creatures are never hurt. A cat, a dog, a pigeon or an ant gets out of the way, and a test puts each of them through dozens of kinds of trouble, from a hammer to an oven. That rule is ours, not a finding from research, and it is what lets us answer "no violence" when the stores ask about the game for its rating. [Under the hood](<#hood-safety>) Safety lines say what happens, then what a grown-up does Under the hood ### Safety lines say what happens, then what a grown-up does Each line lives beside the physics that triggers it: the pan fire with the fire simulation, chlorine with the chemistry, the battery and the hot wire with the electricity. Each carries a note asking translators to keep it just as clear, and the translators' rules say the same. The pan-fire line is spoken when the simulation sees water land on burning oil, and it waits at least a minute before it can come again. Automated tests check each line against the physics that triggers it. Creatures keep out of harm through one shared danger channel that every tool writes to, and a test puts each creature through dozens of kinds of trouble. ### Water on burning oil *"Water on burning oil turns to steam at once and throws the burning oil up\! If a pan catches fire, call a grown-up: they put a lid on it and turn off the heat. Never use water."* ### Bleach meets vinegar or lemon *"Bleach and vinegar $or lemon$ make chlorine gas: it stings your eyes and lungs\! Open the window, or get out into fresh air."* ### The first battery *"Only small batteries are for playing with. Never put anything into a plug socket in the wall: that electricity can really hurt you."* ### Wire glowing on a battery *"Hot\! Wire on a battery can burn. Only try it with a grown-up."* ![In the game, a yellow-green cloud of chlorine over the spot where vinegar was dripped onto bleach, and the painter's speech bubble: Bleach and vinegar $or lemon$ make chlorine gas: it stings your eyes and lungs\! Open the window, or get out into fresh air.]() **The line arrives with the cloud.** Vinegar dripped onto bleach on the page, a yellow-green cloud of chlorine over the spot, and the painter says what it does and to open a window. ### We haven't measured whether children learn safety from it We have no study of our own, and nothing in this page shows that the game changes what children do. The research we found later cuts both ways, and a fair page shows both. In one study, children aged 5 to 8 who watched a video where people acted dangerously, got hurt and then showed the safe way said they would take fewer risks, and spotted more hazards ^{[Potts 1998]()}. Our lines have that shape, consequence then the safe action, though in our game nobody gets hurt. In another, children aged 6 to 9 who watched risky television said they were more willing to take physical risks ^{[Potts 1994]()}. Preschoolers carry more of a story's lesson over to the real world when the story's world is like ours ^{[Walker 2015]()}, so the game's realism may help a safety line travel, and other things too. So our rule is that these things stay on screen, and that a grown-up talks them through. That is a rule of ours, not a finding. ![Painted illustration of the painter putting a closed bleach bottle away on a high shelf, the vinegar kept on another shelf, beside an open window.]() **On screen, bleach and vinegar make a cloud.** At home, they're kept apart. The game says why the first time it happens. 0 Advertising or analytics libraries from other companies in the game. 3 Asks in all, ever, each with a permanent "don't ask again". 7 days At least between two asks. 252 Different sums the gate can ask, from 31 to 99. 32 Country codes where anonymous counting starts switched off, plus every unknown one. 14 days To withdraw from a web purchase, with a button for it in the grown-ups' area. Shared: temperature \+ oil \+ water ### Pour water on burning oil It flares, and the painter says what a grown-up does instead. *[Heat and fire]()* · pinned by a test Shared: acid \+ bleach → chlorine ### Drip vinegar onto bleach A yellow-green cloud of chlorine hangs over the spot, and the line says to open a window. *[Chemistry and pH]()* · pinned by a test Shared: current \+ heat ### Clip a battery to steel wool The wire glows hot, and the line says only with a grown-up. *[Electricity]()* · pinned by a test Shared: one shared danger channel ### Press something down on an ant The ant scurries out from under it, whatever tool it was. *[Animals with their own minds]()* · pinned by a test Shared: merged manifest ### Build the Android app A test fails if an advertising-ID permission sneaks back in. *[How we keep it right]()* · pinned by a test ## A few choices go against the strictest advice, such as an easier sum for parents, and each is listed with why On a research page, "simplifying" means the places we decided against the research's strictest advice. Each was a deliberate call, and each is on this list so a reader can judge it. **The research said.** A gate a ten-year-old can't casually solve **We built.** A two-digit number plus a round ten, at most 100, three tries **Why that's the right call, and what it costs.** Parents use it many times; a hard sum is a tax on them. It is a real hurdle for a five-year-old, not for an older child, and what's behind it carries no pressure. **The research said.** No sign of the paid tools in the child's space **We built.** A static "\+N" tile with reading glasses at a tab's end, no pictures, words or price **Why that's the right call, and what it costs.** A grown-up can see where there's more without a hunt. It sits between rungs 1 and 2 of the ladder, and we say so. **The research said.** Never ask at launch **We built.** From the third launch, a words-only reminder on the start screen's strip **Why that's the right call, and what it costs.** It shows no price and spends one of only three asks. It is still on a screen a child sees. **The research said.** Keep analytics out **We built.** First-party anonymous totals, on by default outside the listed countries **Why that's the right call, and what it costs.** Knowing which tools are used guides what gets fixed. No identifier, day-level only, and a grown-up's switch always wins. **The research said.** A welcome gift on day 1 **We built.** The gift on the second launch, at least 20 minutes after the first, unannounced **Why that's the right call, and what it costs.** The first launch is kept for the welcome. Because it isn't promised beforehand, it can't work as "come back tomorrow". **The research said.** Three equal buttons on an offer **We built.** One bold buy button, with a plain, readable "Not now" under it **Why that's the right call, and what it costs.** A clear main action is easier for a tired parent. It isn't equal, and we don't claim it is. **The research said.** One price **We built.** One product, priced per market $€5.99 on the web, lower in four countries; local prices in the stores$ **Why that's the right call, and what it costs.** A fair price where the family lives. "One price everywhere" would not be true, so we don't say it. ## Each rule and study is listed, with whether we designed to it or found it afterwards Each entry says how it relates to what we built: **applied** $we designed to it$, **informed** $it shaped our thinking$, **found later** $read after building; it fits, or raises a question$, or **cuts against** $it disagrees with something we built$. These are rules and studies of other people's apps. None of them is a study of Professor Oops, and we don't claim to comply with any law here; we read the rules and designed to them. ### Children and commercial pressure - Directive 2005/29/EC $Unfair Commercial Practices$, Annex I, point 28. European Parliament and Council, 2005.[eur-lex.europa.eu/eli/dir/2005/29/oj/eng]()AppliedAlways unfair: a direct exhortation to children in an advert to buy, or to persuade adults to buy. The reason for no "ask a grown-up" anywhere and for the tile's design. - CPC Network, "Key principles on in-game virtual currencies", 21 March 2025.[commission.europa.eu/document/download/8af13e88-6540-436c-b137-9853e7fe866a\_en?filename=Key%20principles%20on%20in-game%20virtual%20currencies.pdf]()AppliedPrinciple 7: design must respect children's vulnerabilities, and age gates and parental controls don't reduce that duty. The game has no virtual currency; we applied its reasoning, which is why a gate in front of a lure doesn't make it fair. - Authority for Consumers and Markets $ACM$, fine on Epic Games over Fortnite, 14 May 2024.[acm.nl/en/node/25515]()Applied€1,125,000 in two fines for direct purchase pressure on children $"Get it now", "Buy now"$ and misleading countdown timers. The reason for no timers and no "only today". - Office of Fair Trading, "Principles for online and app-based games" $OFT1519$, 2014, adopted by the CMA.[gov.uk/government/publications/principles-for-online-and-app-based-games]()AppliedPrinciple 4, commercial information clear and apart from gameplay; principle 6, with its example of an unhappy cartoon character used to push a purchase; principle 7, no direct exhortation. Why the welcome has no price and no character ever asks. - UK CAP Code, section 5 $children$. Committee of Advertising Practice.[asa.org.uk/type/non\_broadcast/code\_section/05.html]()AppliedNo direct appeal to children to buy; children must not be encouraged to copy unsafe practices. Used for the offer's wording and for store videos. - FTC staff, "Bringing Dark Patterns to Light", September 2022.[ftc.gov/system/files/ftc\_gov/pdf/P214800%20Dark%20Patterns%20Report%209.14.2022%20-%20FINAL.pdf]()AppliedDefines nagging as a request "that doesn't let the user permanently decline", and parasocial relationship pressure. The reason every ask has "No thanks, don't ask again". - FTC, Epic Games settlement, 19 December 2022.[ftc.gov/news-events/news/press-releases/2022/12/fortnite-video-game-maker-epic-games-pay-more-half-billion-dollars-over-ftc-allegations]()Informed$275 million COPPA penalty and $245 million in refunds. Shaped the fixed order: the sum, an offer with the price, then the store's own sheet. - Apple, App Store Review Guidelines, 1.3, 1.4.5, 2.3.8 and 5.1.4.[developer.apple.com/app-store/review/guidelines]()AppliedKids Category rules on third-party analytics and ads $the text says "should not", with limited cases; the game has neither$, and on never framing risky acts as a challenge. - Apple, "Kids apps" $parental gates$.[developer.apple.com/app-store/kids-apps]()Applied*Applied, with a deviation.* "Adult-level tasks that must be completed." The gate exists; we made it easier than our own research asked, on purpose. - Google Play, Families policy.[support.google.com/googleplay/android-developer/answer/9893335]()AppliedRules on what may appear at launch, no emotionally manipulative offers, and monetisation kept distinguishable from play. The reason the first-launch welcome has no price. - Brazil, Lei 15.211/2025 $ECA Digital$.[www2.camara.leg.br/legin/fed/lei/2025/lei-15211-17-setembro-2025-797997-publicacaooriginal-176498-pl.html]()AppliedArt. 20 bans loot boxes in games aimed at or likely to be used by children; art. 17 asks for tools to limit and monitor time of use. One fixed product, and the play-time limit. ### Research on children's apps and persuasion - Radesky J, Hiniker A, McLaren C, et al. "Prevalence and Characteristics of Manipulative Design in Mobile Applications Used by Children." JAMA Network Open 5$6$:e2217641, 2022.[doi:10.1001/jamanetworkopen.2022.17641]()Applied133 apps played by 160 children aged 3 to 5; 26 of 133 $19.6 %$ had none of the manipulative designs coded. Killed the locked present and the daily gifts. The authors call the socioeconomic results exploratory. [doi:10.1001/jamanetworkopen.2022.17641]() - Meyer M, Adkins V, Yuan N, Weeks HM, Chang YJ, Radesky J. "Advertising in Young Children's Apps: A Content Analysis." J Dev Behav Pediatr 40$1$:32–39, 2019.[doi:10.1097/DBP.0000000000000622]()Informed135 apps reviewed in all $a 39-app pilot and the 96 most downloaded in Google Play's "5 and under"$; 129 $95 %$ carried at least one kind of advertising. An exploratory study. [doi:10.1097/DBP.0000000000000622]() - Mallinckrodt V, Mizerski D. "The effects of playing an advergame on young children's perceptions, preferences, and requests." J Advertising 36$2$:87–100, 2007.[doi:10.2753/JOA0091-3367360206]()Found later*Found later: a caution.* 295 children aged 5 to 8: the game raised brand preference among older children only, and made no difference to intention to ask for the product. The science of pester power is less settled than the law's position; we follow the law. [doi]() - Rozendaal E, Buijzen M, Valkenburg P. "Children's understanding of advertisers' persuasive tactics." Int J Advertising 30$2$:329–350, 2011.[doi:10.2501/IJA-30-2-329-350]()Found later*Found later: fits.* 209 children aged 8 to 12: understanding grows from 8 to 12, with a clear rise around 10. Backs treating our audience as not yet equipped; under-8s weren't studied. [doi]() ### Privacy - European Data Protection Board, Guidelines 2/2023 on the technical scope of art. 5$3$ ePrivacy Directive, version 2.0, adopted 7 October 2024.[edpb.europa.eu/our-work-tools/our-documents/guidelines/guidelines-22023-technical-scope-art-53-eprivacy-directive\_en]()AppliedWhy the counts start off across most of the EEA. - GDPR $Regulation 2016/679$, art. 8 and recital 58.[gdpr-info.eu/recitals/no-58]()AppliedRecital 58 asks for language a child can understand: the privacy page's "For children" box. - FTC, Children's Online Privacy Protection Rule $as amended 2025$.[ftc.gov/legal-library/browse/rules/childrens-online-privacy-protection-rule-coppa]()AppliedAn internet address is a persistent identifier; it is used only for internal operations, as the privacy page says. - Apple, App privacy details.[developer.apple.com/app-store/app-privacy-details]()AppliedThe store label for the counts: Usage Data, Product Interaction, not linked to the user. - Reyes I, et al. "'Won't Somebody Think of the Children?' Examining COPPA Compliance at Scale." PoPETs 2018$3$:63–83.[doi:10.1515/popets-2018-0021]()Found later*Found later: fits.* 5,855 popular free children's Android apps; a majority potentially in violation, mainly through third-party SDKs. Fits the choice of no SDKs; it is about other apps, not an audit of ours. [doi]() ### Breaks and safety - Hiniker A, Suh H, Cao S, Kientz JA. "Screen Time Tantrums." CHI 2016, 648–660.[doi:10.1145/2858036.2858278]()Found later*Found later: raises a question.* 27 parents interviewed and 28 families' diaries, children 1 to 5: transitions ended by technology went better than parent-ended ones, and parents' two-minute warnings made things worse. Our warning comes from the device, and our players are older; the question stays open. [doi]() - NFPA, Educational Messages Desk Reference, 2026 edition.[nfpa.org/-/media/project/storefront/catalog/files/home-fire-safety/emac/educationalmessagesdeskreference.pdf]()Found later*Found later: fits, in part.* 8.4.1: slide the lid over, turn off the burner, leave it until cooled; 8.4.2: never pour water on it. Matches the lid and no water. It says nothing for the towel on pan fires. - Brandweer Nederland, "Vlam in de pan".[brandweer.nl/onderwerpen/vlam-in-de-pan]()Found later*Found later: fits, in part.* Turn off the heat, cover the pan with a lid, a baking tray or a sturdy tray, never use water. Matches the lid and no water; it mentions no cloth. - Essex County Fire and Rescue Service, safety warning after a chip-pan fire, 11 July 2024.[essex-fire.gov.uk/news/firefighters-issue-safety-warning-after-woman-injured-chip-pan-fire]()*Cuts against.* "Never throw water or a damp tea towel over it." Contradicts the game's "Damp tea towel" button. One regional service's release; the others above are silent on towels. - Chang A, et al. "Cleaning and Disinfectant Chemical Exposures and Temporal Associations with COVID-19." MMWR 69$16$:496–498, 2020; and CDC, Facts about chlorine.[cdc.gov/mmwr/volumes/69/wr/mm6916e1.htm]()Found later*Found later: fits.* Don't mix cleaning products; bleach with some cleaners releases chlorine; get to fresh air. Matches the game's chlorine line. - Potts R, Swisher L. "Effects of televised safety models on children's risk taking and hazard identification." J Pediatr Psychol 23$3$:157–163, 1998.[doi:10.1093/jpepsy/23.3.157]()Found later*Found later: fits in shape.* 60 children aged 5 to 8: dangerous behaviour, its consequence, then the safe behaviour lowered willingness to take risks and raised hazard identification. Self-report, short term; in our game nobody gets hurt. [doi]() - Potts R, Doppler M, Hernandez M. "Effects of television content on physical risk-taking in children." J Exp Child Psychol 58:321–331, 1994.[doi:10.1006/jecp.1994.1037]()*Cuts against the comfortable story.* 50 children aged 6 to 9: high-risk television raised self-reported willingness to take physical risks. Why "it stays on screen" is our rule, not a finding. [doi]() - Walker CM, Gopnik A, Ganea PA. "Learning to learn from stories." Child Development 86$1$:310–318, 2015.[doi:10.1111/cdev.12287]()Found later*Found later: cuts both ways.* 108 preschoolers generalised more from stories whose world resembled reality. Realism may help a safety line travel, and other cause and effect too. [doi]()