Dimension 9 browser game uses Claude Opus 5.5 to generate rooms and monsters

Dimension 9 is a browser-based game inspired by the Backrooms that requires no installation and runs on PC and phone, according to its developer. The project uses Anthropic's Claude Opus 5.5 AI model to create and expand the game world. The developer set 15 initial rooms as a foundation, but the AI now generates new rooms, characters, and creatures based on player behavior. The developer stated that they no longer know what appears in the game.

Photo: Javier Martínez on Unsplash

Players can explore alone or in multiplayer mode. The developer says voice chat uses distance-based audio, making it harder to hear others as players move apart. Equipment includes a map, logbook, scanner, EMP scan, flashlight, and camcorder. A loading screen displays July 20, 1969, 20:17 UTC. The game's website maintains an archive of discoveries that currently lists four entries: The Atrium, The Pilgrims, The Sleeper, and The Smear.