🌐 Browser2013OrteilFIDDLYCookie Clicker rebuild deck
FIDDLY
The design is a spreadsheet and prompts beautifully; the one thing that kills builds is native JavaScript numbers losing integer precision at 2^53, which an idle game passes within the hour.
You will get it, but one specific system will fight you.
Idle games are the most promptable genre that exists, because the entire design is a spreadsheet. The one thing to insist on is big-number math on day one — every incremental that skips it hits a wall where the numbers go NaN and the save file dies. The writing is what makes Cookie Clicker good, and that part is on you.
- Difficulty
- FIDDLY · 2 of 5
- First playable
- A weekend
- The original
- 2 team-years
- Released
- 2013 · Browser
- Genre
- Incremental
Build an incremental/idle clicker game. Single HTML file, vanilla JS, saves to localStorage. Requirements: - Use a big-number library (break_infinity.js style) from the start. Native JS numbers lose integer precision at 2^53 and an idle game passes that in an hour — retrofitting this later is a rewrite. - Core loop: click for 1 unit. Ten buildings, each with a base cost, a cost growth of 1.15x per purchase, and a per-second production. Costs and production must follow a clean geometric curve so the tenth building is worth thousands of the first. - Upgrades that multiply: per-building multipliers, global multipliers, click-power multipliers, and synergies where building A boosts building B. Gate them behind ownership and total-earned thresholds. - Offline progress: on load, compute elapsed time since last save and grant production at a stated efficiency, with a "while you were away" summary. - Prestige: reset everything for a permanent currency based on a fractional power of lifetime earnings, spent on a permanent upgrade tree. The prestige threshold should first be reachable in about two hours. - Golden-cookie style random events every 60-180 seconds giving a temporary 7x multiplier for 30 seconds — clicking these is the only active skill in the game. - Number formatting: 1.234 million / billion / trillion, then scientific notation, switchable. - Achievements that grant small permanent bonuses, and a stats panel showing production breakdown per building. Definition of done: I prestige once, and the second run reaches the same point four times faster.
- A decade of accumulated absurdist writing, which is the actual product
- Balance across 15 orders of magnitude that stays interesting the whole way
- The prestige and heavenly-upgrade metagame layered on over years
The eight-second windfall that rewards attention
An idle system runs whether or not anyone is watching, which makes it a spreadsheet. The rare, brief, high-value event that pays you for looking is the one part that is actually a game, and it drops into anything where you want a system to occasionally deserve attention rather than constantly demand it.
ScopeAn evening— build just this, not the game
Build an attention-reward layer over an idle resource as a single self-contained HTML file. Vanilla JS, localStorage, no build step. - A resource that accrues automatically at a rate you raise by spending it. Keep this part deliberately boring, about twenty lines. - The mechanic: at a randomised interval between 60 and 180 seconds, a small target appears somewhere on the page for 8 seconds. Clicking it grants one of three weighted effects: a 7x production multiplier for 30 seconds, an instant payout of 15 minutes of production, or a 30-second window where each click pays a full second of production. - Buffs stack multiplicatively, each with a visible countdown. - Attribution is the interesting part: track lifetime income split into passive, multiplier-boosted, and instant payout, shown as live percentages. - Persist everything including the timestamp of the next spawn, so reloading cannot farm it. Definition of done: after twenty minutes of half-attention, the attribution readout shows more than a third of my income arrived through those eight-second windows.
Not a clone — Cookie Clicker 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. 24,360 ways to land.
Fealty Play By Mail
Cookie Clicker, but asynchronous multiplayer — no live server, set in a medieval kingdom at war. Rendered in clean product UI 3D.
Build a browser game called "Fealty Play By Mail". The pitch in one line: a incremental in the spirit of Cookie Clicker, but asynchronous multiplayer — no live server, set in a medieval kingdom at war. WHAT THIS IS Take the SHAPE of Cookie Clicker — 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 Asynchronous multiplayer — no live server. Players take turns hours apart against stored state. You get real multiplayer with none of the real-time netcode. 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 A medieval kingdom at war. Castles, levies and oaths. Siege logistics and feudal politics matter as much as the sword arm. 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 Clean product UI 3D. Soft studio lighting, muted brand palette, UI chrome that looks shippable, and zero grit — intentional polish. 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.
- break_infinity.js — big-number math for incrementals
- The Incremental Game Design wiki (r/incremental_games resources)
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 2 team-years to the counter on the homepage.
Then try these
Questions
How hard is Cookie Clicker to rebuild with an AI agent?
Yes — every game is buildable at some scope. The question is how hard, and Cookie Clicker is FIDDLY (2 of 5). You will get it, but one specific system will fight you. The design is a spreadsheet and prompts beautifully; the one thing that kills builds is native JavaScript numbers losing integer precision at 2^53, which an idle game passes within the hour. Reckon on a weekend to something you can actually play — not to something that matches the 2 team-years Orteil spent.
What makes Cookie Clicker hard to rebuild?
The design is a spreadsheet and prompts beautifully; the one thing that kills builds is native JavaScript numbers losing integer precision at 2^53, which an idle game passes within the hour. That is why it sits at FIDDLY rather than a tier either side of it. If you want the idea without the project, the transferable part is the eight-second windfall that rewards attention — an evening of work.
How long does it take to build a Cookie Clicker clone?
Wrong question, and it is worth saying why. Nobody rebuilds Cookie Clicker — the original took Orteil on the order of 2 team-years, released in 2013 on Browser. What you can do is reach something playable and genuinely yours in about a weekend, 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 Cookie Clicker?
A decade of accumulated absurdist writing, which is the actual product. Balance across 15 orders of magnitude that stays interesting the whole way. The prestige and heavenly-upgrade metagame layered on over years. 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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