Games · AI · Browser falling-block game / AI agent experiment

BlockDrop

A flashy falling-block game for the browser. One Claude Opus agent built the playable version from a single prompt in under an hour, with no revisions.

< 1 h one prompt, one agent

TypeScript Canvas 2D Web Audio Claude Opus

Play in the browser

BlockDrop on a desktop screen: glossy coloured blocks stacked in a glowing well, a ghost piece, a shockwave ring and particles from a landing, with hold, score and next-piece panels

BlockDrop on a phone: one slim strip on top with hold, next pieces and score, the board filling the screen and a button bar under it

The BlockDrop start card on a phone with Start and High scores buttons

Role: Solo developer, built with one Claude Opus agent
Workflow: AgentAutoSetup scaffold, one prompt, no revisions
Platform: Browser · desktop and phone
Size: No runtime dependencies, 17 kB of gzipped JS

Overview

BlockDrop follows the genre’s modern standard rules (the “guideline”): a 7-bag randomizer, SRS rotation with wall kicks, hold, a ghost piece, lock delay, T-spins, back-to-back chains and combos. It wraps them in a canvas renderer with particles, screen shake and easing, and every sound is synthesized through Web Audio, so the game ships without a single asset file.

One prompt, one agent

The repository was scaffolded with AgentAutoSetup: an agent manual, enforced safety rules, git hooks and verification gates from the first commit. Then one Claude Opus agent got one prompt. In under an hour, with no revisions, it delivered the playable version:

the complete rule set, including T-spin grading, perfect clears and guideline scoring
pre-rendered block sprites, pooled particles, an eased row collapse, hard-drop trails and a score that rolls up
keyboard play with auto-repeat, a visible focus ring and a live region that announces the game state
111 behavioural checks on the rules, plus gates for purity, reduced motion and the on-screen controls list
touch controls and gestures
an online high-score board

Each new gate was first run against a deliberately broken copy to prove it could fail. The rules gate caught two bugs before they were committed: a double clear removed the wrong second row, and the O piece rotated around its box instead of staying put. The process ran fully autonomously from start to finish.

Built to be checked

The rules are pure: no DOM, no clock and no hidden randomness. Time arrives as a delta and randomness as a seed, so every game is reproducible and the rules run in Node in milliseconds. The dependency points one way, so the whole presentation layer could be deleted and the game would still play correctly, and a gate makes sure it stays that way.