📱 Mobile2013Dong NguyenEASYFlappy Bird rebuild deck
EASY
Nothing here is hard: the whole game is a gravity constant and an impulse that replaces vertical velocity rather than adding to it, and you find both by feel in an hour.
You will get essentially the whole thing.
The smallest genuinely great game ever made and a perfect first agent build. Everything is in two constants, and if it feels wrong the fix is always gravity or impulse, never the code. Ask for a tuning panel with sliders for both and you will spend a happy hour finding the original numbers by feel.
- Difficulty
- EASY · 1 of 5
- First playable
- An evening
- The original
- 1 team-years
- Released
- 2013 · Mobile
- Genre
- Arcade
Build a one-button endless flyer in the Flappy Bird mould. Single HTML file, Canvas 2D, playable on phone and desktop. Requirements: - Physics: constant downward gravity, a fixed upward impulse on tap that REPLACES vertical velocity rather than adding to it. This one detail is why the original feels the way it does — do not use additive impulse. - Bird rotation driven by velocity: nose up sharply on flap, tilting toward straight down as it falls, clamped at +25 and -90 degrees, with the downward rotation lagging so it feels heavy. - Pipes spawn at a fixed interval with a random gap centre inside a safe band, scroll left at constant speed, and are recycled from a pool. The gap size never changes — the game has no difficulty curve and that is deliberate. - Collision as an AABB slightly smaller than the sprite, so near-misses read as fair. - Three states: ready with a hovering bird and a tap prompt, playing, and dead with a freeze-frame, a fall, and a score card showing score, best, and a medal. - Feel: 60ms hit-stop on death, a small white flash, screen shake, and a passing whoosh on each pipe cleared. - Web Audio for flap, score, hit and die. No files. - Touch, click, and space all flap. Restart in one tap, always under 200ms — the retry loop is the product. Definition of done: I say "one more go" out loud without meaning to.
- The 2014 App Store moment, which is not a feature you can implement
- The exact gravity and impulse constants, which are the entire game and were tuned by hand
- Nothing else
Death to next attempt in under 200ms
In a game you fail at constantly, the retry loop is the product. A fade and a menu turn forty attempts into four; a restart that beats a blink turns frustration into one more go, and unlike most feel work it is a latency budget you can actually measure.
ScopeAn evening— build just this, not the game
Build a restart-latency testbed around a deliberately trivial failable game. Single self-contained HTML file, Canvas 2D, no dependencies. - The game is one input, one hazard, dead in seconds. It exists only so you can fail repeatedly. - Three restart flows, switchable live: full teardown with a fade, a menu and a play button; fade with an automatic restart after 1200ms; and instant, where death holds a 60ms freeze frame and the next input both dismisses and starts, resetting state by overwriting pooled objects. - Instrument it. Measure milliseconds from the dismissing input to the first frame of live play, keep the last twenty, and show median and worst. - Nothing may allocate during an instant restart. Preallocate every object at boot and display a live object count to prove it. Definition of done: the instant flow has a median under 200ms and a flat object count across fifty deaths, while full teardown is at least five times slower on the same machine.
Not a clone — Flappy Bird re-themed and cut down to something you can finish. The angle is the important reel: it is what turns a project into a weekend. 5,880 ways to land.
Gaslight Endless
Flappy Bird, but an endless survival mode instead of levels, set in Victorian gothic. Rendered in risograph two-colour print.
Build a browser game called "Gaslight Endless". The pitch in one line: a arcade in the spirit of Flappy Bird, but an endless survival mode instead of levels, set in Victorian gothic. WHAT THIS IS Take the SHAPE of Flappy Bird — its core loop, and whatever makes that loop good — and rebuild it as your own game in a different world at a smaller scope. Use your own names, art and audio, which you want anyway: a reskin of somebody else's game is less interesting than a new one that works the same way. THE ANGLE — this is the important constraint, honour it above everything else An endless survival mode instead of levels. One arena, escalating waves on a data-driven timeline, a run timer and a score. Replaces level design with a difficulty curve. This is what makes the project finishable. If a decision would push the scope back towards the original's, take the smaller option every time. THE THEME Victorian gothic. Fog, gaslight and etiquette. Social rules that constrain movement as hard as walls do. The theme is not a coat of paint. Let it change what the mechanics mean — a reload, a health pack and a locked door should all be things that make sense in this world and nowhere else. LOOK Risograph two-colour print. Two spot inks with visible misregistration, halftone dot shading, and paper texture showing through every fill. REQUIREMENTS - Runs in a browser with no build step. Canvas 2D unless the angle genuinely requires 3D, in which case three.js. - Fixed-timestep update loop with interpolated rendering, so it behaves the same at 60Hz and 144Hz. - Every tuning constant in one CONFIG object at the top, exposed as live sliders in a debug panel. You will find the feel by dragging those, not by prompting. - All content — levels, entities, balance numbers — in JSON or plain data files, never inline in the logic. - Audio generated with the Web Audio API rather than asset files. - Respect prefers-reduced-motion: keep the fades, drop the shake and the parallax. BUILD ORDER 1. The core loop with placeholder rectangles, at the reduced scope the angle demands. No theme, no art, no audio. Make it fun as rectangles first. 2. The angle's consequences. Cutting to bots, or to turn-based, or to one level changes the design rather than just shrinking it — find out how and rewrite step 1. 3. The theme, as content and data. 4. The look, applied last as a rendering layer over a game that already works. Start by writing a one-page plan: the core loop, what the angle removes and what that frees you to do properly, and what you are deliberately leaving out. Wait for me to approve it before writing code.
Half the time one of these already does what you wanted, and the other half it saves you a week of solving a problem someone documented in 1997.
One count per game. No account — it is tied to a salted hash of your IP, which is not stored in a form anyone can reverse. Every build adds 1 team-years to the counter on the homepage.
Then try these
Questions
How hard is Flappy Bird to rebuild with an AI agent?
Yes — every game is buildable at some scope. The question is how hard, and Flappy Bird is EASY (1 of 5). You will get essentially the whole thing. Nothing here is hard: the whole game is a gravity constant and an impulse that replaces vertical velocity rather than adding to it, and you find both by feel in an hour. Reckon on an evening to something you can actually play — not to something that matches the 1 team-years Dong Nguyen spent.
What makes Flappy Bird hard to rebuild?
Nothing here is hard: the whole game is a gravity constant and an impulse that replaces vertical velocity rather than adding to it, and you find both by feel in an hour. That is why it sits at EASY rather than a tier either side of it. If you want the idea without the project, the transferable part is death to next attempt in under 200ms — an evening of work.
How long does it take to build a Flappy Bird clone?
Wrong question, and it is worth saying why. Nobody rebuilds Flappy Bird — the original took Dong Nguyen on the order of 1 team-years, released in 2013 on Mobile. What you can do is reach something playable and genuinely yours in about an evening, and then keep going for as long as it stays interesting. Any figure that claims otherwise is measuring a prototype and calling it a game.
What do I lose by building my own Flappy Bird?
The 2014 App Store moment, which is not a feature you can implement. The exact gravity and impulse constants, which are the entire game and were tuned by hand. Nothing else. Those are the parts a prompt will not hand you.
Which AI coding agent should I use to build it?
Any of Claude Code, Codex or Cursor will handle this prompt. Paste it as your first message, let the agent scaffold the project, then iterate on feel — the second, third and tenth prompts are where a game actually gets good. Work in an empty folder or a fresh git branch so you can throw it away cheaply.
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