I vibe coded a free offline Math game for kids

A developer created Escape Run, a free, open-source, offline math game for kids that uses adaptive difficulty and evidence-based skills while prioritizing privacy with no ads, sign-ins, or tracking. The game, built almost entirely by prompting an AI coding agent, runs in the browser as a PWA and stores all progress locally. It aims to provide a respectful, educational alternative to ad-filled children's apps.

A free, open-source, privacy-first learning game where kids drive a little car across three lanes and steer into the lane with the right answer. Five evidence-based math skills, adaptive difficulty, spaced review — and no ads, no sign-in, no tracking . Everything runs in the browser and works offline. ▶ Play: https://abhas9.github.io/escape-run/ https://abhas9.github.io/escape-run/ · ~35 KB core code + ~1.5 MB lazy-loaded audio · zero runtime dependencies · installable PWA 🤖 Vibe-coded— built almost entirely by prompting an AI coding agent, then kept honest with unit tests and headless-browser smoke tests. See How it was built . Most "free" kids' math apps are stuffed with ads, upsells, accounts, and trackers pointed at children. I wanted the opposite: something my kid could open and play in one tap, that respects their attention and privacy, and that's actually grounded in how children learn math — with the whole thing open for other parents and teachers to read, fork, and improve. Privacy by design. No accounts, no analytics, no network calls. All progress is stored in localStorage on the device. Nothing ever leaves the browser. Verify it yourself — open DevTools → Network. Evidence-based content. The eight skills are chosen because they're strong, well-replicated predictors of early-elementary math achievement, and they map onto the India NCERT primary-maths curriculum see below . It teaches, not just tests. A friendly mascot Pip guides a hands-on tutorial, explains a wrong answer with a visual and a second chance, offers optional hints, and gives a quick modeled example when a skill levels up. Ethical stickiness, no dark patterns. Mastery-based progression, adaptive difficulty, spaced review, a Daily Challenge, rotating Quests, a Trophy Room, and collectible characters — all earned and local, with flexible streaks that never punish or guilt, and no purchases ever. Tiny & hackable. Vanilla JS + Canvas, no framework, no build step. Every skill is a ~40-line module. Accessible. Keyboard play, reduce-motion, high-contrast, colour-blind-safe cues ✓/✗, not colour alone , easy-read text, and large tap targets. Warm audio, still private. Calm background music, sound effects, and a voiced tutorial generated with ElevenLabs are baked in as local files at build time — the browser never calls any audio API, and a procedural WebAudio synth fallback keeps things working if the files are absent. | Skill | In game | Why it's here | |---|---|---| Subitizing / Counting | Number Fuel — "how many dots?" | Instantly seeing "how many" is a unique predictor of later achievement beyond rote counting. | Magnitude comparison | Big & Small — tap the bigger/smaller number | Numerical magnitude is one of the strongest single predictors of math outcomes. | Arithmetic fluency | Speed Math — quick add/subtract | Fluency frees working memory for harder math. | Patterning | What's Next? — extend the pattern | Builds algebraic reasoning and executive function. | Number bonds / make-10 | Make It Whole — part-whole composition | Composing/decomposing number is core number sense. | Multiplication & division | Super Groups — equal groups, times tables, fair sharing | Repeated addition → multiplicative thinking; the gateway to Class 2–3 maths. | Shape & space | Shape Shadows — name shapes, corners, silhouettes, solids, equal parts | Early geometry & spatial sense; a gentle on-ramp for the youngest players. | Fractions | Fair Share — halves, quarters, sharing a group | Fair-share intuition is the foundation for rational number. | The last three roads start locked and open as mystery roads on the Adventure Map when their prerequisites are met e.g. Super Groups opens at Speed Math level 4 , so a child meets one new idea at a time. Unlocking one is a little celebration of its own. Upper levels 6–7 . Each skill extends past its original cap for kids who master the basics: doubles & halves and missing-number equations ? + 4 = 9 — early algebraic reasoning in Speed Math , bridging through ten and place-value parts 30 + ? = 34 in Make It Whole , counting in rows of ten in Number Fuel , transposed-digit comparisons 34 vs 43 in Big & Small , and descending & two-attribute patterns in What's Next? . Number-line estimation Siegler & Booth is on the roadmap but not yet in the game. Curriculum mapping India NCERT . Each road maps onto a primary-maths strand, so the play is transparent to parents and teachers: | Road | NCERT strand | |---|---| | Number Fuel | Numbers 1–20 · Class 1 | | Big & Small | Comparing Numbers · Class 1–2 | | Speed Math | Addition & Subtraction · Class 1–2 | | What's Next? | Patterns · Class 1–3 | | Make It Whole | Making 10 / Number Bonds · Class 1–2 | | Super Groups | Grouping & Sharing × ÷ · Class 2–3 | | Shape Shadows | Shapes & Space / Shadows · Class 1–3 | | Fair Share | Fair Share — halves & quarters · Class 3 | Content stays within the Class 3 ceiling on purpose: no remainders, no fractions beyond halves/quarters, tables to ten. How difficulty, review & feedback work Adaptive difficulty ZPD . Each skill levels up after a short run of successes and gently eases back after repeated misses, keeping the child in the "just-right" zone Vygotsky's zone of proximal development . Mastery, not grinding. Progress reflects demonstrated understanding Bloom's mastery learning , not time spent. Spaced review. A Leitner-style scheduler resurfaces skills as they come due , distributing practice over time the spacing effect . Teach, don't just test. Wrong answers get a friendly visual explanation and a second chance; an optional hint appears only when a child hesitates not on every question ; a quick modeled example appears when a skill levels up "I do / we do / you do"; Shute's formative feedback . Staying engaged ethically Onboarding with a mascot Pip who then rides along and reacts. "Play" rotates through skills and shows which one is next. Daily Challenge — one date-seeded mission a day with a bonus. Quests — three rotating goals that refresh daily. Balloon-pop bonus round after every mission for extra stars. Trophy Room — sticky achievement badges. Collectible characters, cars & worlds with a celebratory earned reveal. Grown-up controls — adjustable car speed Relaxed/Steady/Normal , break reminders, and accessibility toggles.- All earned and local; streaks never punish; nothing is ever purchasable. Selected references: Bloom, Learning for Mastery 1968 ; Vygotsky, Mind in Society 1978 ; Cepeda et al., Distributed practice Psych. Bulletin, 2006 ; Siegler & Booth on number-line estimation; Rittle-Johnson on patterning; Schneider et al. meta-analysis on magnitude comparison. Full write-up in the in-game Grown-ups panel. Touch: tap the left / middle / right of the screen to change lane, or swipe. Keyboard: ← / → or A / D to move, 1 / 2 / 3 to jump to a lane, P or Esc to pause.- Collect ✦ sparks, dodge cones, and drive into the lane with the correct answer. No build step. Any static server works: python3 -m http.server 8000 then open http://localhost:8000 or: npx serve . Music, SFX, and tutorial narration are pre-generated and committed under assets/audio/ , so you don't need to regenerate them to play. To rebuild them e.g. to tweak prompts , set ELEVENLABS API KEY in a local .env git-ignored and run: node tools/gen-audio.mjs regenerates only missing files node tools/gen-audio.mjs --force sfx:correct force one asset Generation happens at dev time only ; the shipped game plays local files. Pure game logic skill generators, mastery model, spaced-repetition scheduler is covered by Node's built-in test runner — no dependencies required : node --test Optional browser smoke tests live in tests/smoke.mjs and tests/nav.mjs they drive a local Chrome via puppeteer-core , which is not a runtime dependency . index.html entry point canvas + DOM overlay manifest.webmanifest PWA metadata sw.js service worker offline src/ engine/ loop · input · renderer · audio files + WebAudio synth · voice · particles game/ runner · gates · hud · mascot · onboarding · teach · map · garage goals · trophies · balloons · reveal · results · parent zone skills/ counting · comparison · arithmetic · patterning · bonds progress/ mastery ZPD · scheduler Leitner · daily · quests · achievements save · settings ui/ styles · DOM helpers assets/ icons · audio/ music · sfx · voice, generated tools/ gen-audio.mjs dev-only ElevenLabs generator tests/ unit tests node --test + optional browser smoke tests Every skill is a small pure module that returns a challenge. Create src/skills/myskill.js : js import { randInt, makeOptions } from "../util.js"; export const meta = { id: "myskill", name: "My Skill", short: "My Skill", icon: "?", color: " 0ea5e9", maxLevel: 5, blurb: "What this teaches.", }; // rng is a 0..1 function seedable for tests . Return exactly 3 options. export function generate level, rng { const answer = randInt rng, 1, level 3 ; const { options, correctIndex } = makeOptions rng, answer, answer + 1, answer - 1, answer + 2 ; return { skillId: "myskill", level, prompt: { type: "expr", text: ${answer} = ? }, // reuse a render type optionKind: "number", promptText: "Pick the number", say: "Pick the number", options, correctIndex, }; } Register it in src/skills/index.js add to SKILLS and SKILL ORDER , give it a default entry in src/progress/save.js SKILL IDS , and — so it's playable right away — add its id to BASE UNLOCKED in src/progress/unlocks.js or give it an unlock rule to make it a mystery road . It then automatically gets adaptive difficulty, spaced review, a map card, and results tracking. Escape Run was vibe-coded — designed and written almost entirely by prompting an AI coding agent in natural language, iterating feature by feature gameplay, the eight skills, adaptive difficulty and spaced repetition, the mascot-guided tutorial, teaching feedback, the daily/quests/trophies loop, and the ElevenLabs-generated audio . To keep that honest rather than hand-wavy: - The game logic is covered by unit tests skill generators, mastery model, spaced-repetition scheduler, skill rotation, quests, achievements . node --test - Whole-game flows are checked with headless-Chrome smoke tests . - It's deliberately small, framework-free, and readable — every skill is a ~40-line module — so you can audit or fork any part of it. Judge it on the result: tiny, tested, private, and hackable. Escape Run collects nothing . There are no accounts, no ads, no third-party scripts, and no network requests after the initial load the service worker even lets it run fully offline . Progress lives only in this browser's localStorage , and the Grown-ups → Reset progress button clears it. MIT /abhas9/escape-run/blob/main/LICENSE © abhas9. Built for kids and their grown-ups — fork away.