What they did
The poster, u/jacobjr23, wanted a game inspired by the documentary Secret Mall Apartment. Players build a hidden home in the drop ceiling of a failing 2004 mall, tap the shops below for power, send a crew out at night to collect coins from the fountain while a guard patrols, and win by buying the mall at a New Year's Eve auction. The poster kept the design, playtesting and feedback for themselves and gave Claude Opus 5.5 the coding. Claude wrote the simulation, the crew AI, the isometric renderer, a bot that plays the game to check its balance, and a pipeline that pulls sprites from PixelLab. It also produced the trailer by setting up shots inside the running game and generating the music.
How it went
The game is live and free to play in a browser. A first try in March did not work out because the models were not good enough yet, in the poster's view. The second try, started about a week before the post, gave a result they were happy with. The post gives no figures for hours, cost or code size.
Worth knowing
The post names the model but not the tool it ran in, so the harness is unknown. Having the agent write a bot that plays the game is one way to tune the balance without playtesting every change yourself. The art came from an outside service (PixelLab) through a script Claude wrote, not drawn by hand or by the model.