Building a game demo with Claude Code in one day

Description and use

Reptile Catcher was prototyped in a day using Claude Code, then refined and released on itch.io.

Problem

Develop a numbers-heavy incremental game quickly using AI-generated code and assets while maintaining control over design and feature scope.

Outcome

Reptile Catcher was built in one day of AI-assisted coding and design, then polished over a week, demonstrating rapid prototyping and the importance of early balance testing with a bot.

Workflow

• Pull game template at 1:46 PM
• Run core loop; AI writes code
• Add balance simulator bot in next commit
• Iterate bot personalities and use bot to test balance
• Detect and fix bot bug revealing scattered lock rules
• Change direction at 2:20 PM to pixel art and new gameplay mechanics
• Generate pixel sprites via PixelLab + Claude, select and adjust
• Remove unwanted AI-built features (auto‑catching, auto‑selling, offline progress, prestige)
• Polish game: add bosses, backgrounds, fix bugs, prepare screenshots
• Ship demo on itch.io on October 11

Evidence

Five minutes after the template went in, the catch‑sell‑breed loop was running.

Source

The very next commit was a balance simulator where a bot plays the game for you.

Source

I changed direction completely: pixel art, catching as a "run" where you move a character yourself, and upgrades as a tree that branches out like a mind map.

Source

Around 7 PM I removed a whole set of features Claude had built that afternoon: auto-catching, auto-selling, and offline progress.

Source