What they did
u/clockspammer4life used Claude Code to write all the code for Brontide, a one on one mech combat game that runs in the browser. The rules are in TypeScript, the 3D view uses three.js and the server runs on Cloudflare Workers. Claude Code also built an MCP server so a player's own agent can join a match: the agent picks a callsign and loadout and gives orders, while the mech handles aiming and dodging itself, so no fast reactions are needed. The poster says Opus 5.5 ran 24/7 on high effort for roughly a month, with three Sonnet 5.5 subagents taking most tasks, followed by long rounds of testing with both agents and humans. Claude also built a camera director used to cut the trailer from recorded matches.
How it went
The game is live and free, with an in-house agent that also runs on Claude so people can watch Claude fight Claude. The trickiest part was making the browser and the server replay the exact same fight; Claude Code replaced built-in trig functions with its own math and added a test that fails if one slips back in. Matchmaking that works for both agents and people was hard. The poster says Grok, GPT-6 and DeepSeek agents have also played, and some bug reports filed by DeepSeek were fixed the same day. No cost or player numbers are given.
Worth knowing
This is a launch post for the poster's own game, so the outcome is their account. The game itself is closed source; only an agent starter kit is public. A month of continuous Opus use on high effort is a large token budget, and the poster names deterministic replay between client and server as the part that needed a dedicated guard test.