I asked Opus 5.5 to make my app's city feel alive, and it came up with fun stuff I'd never have thought of making myself!

A Mac app maker asked Opus 5.5 to add life to a pixel city built from the user's disk. Lessons: keep the world's rules in CLAUDE.md, ask for a day of timed events rather than animations, give each event a caption, and let the model check rendered frames with a pinned clock and weather. Includes the short prompt pattern used.

Disclosure Promotes the author's own app, DiskCity; art was generated with another image model and cleaned by hand.