Cataclysm 3D, the short version

The full briefing, with timelines, token charts, the agents' own evidence screenshots and recreations of the official screenshots, is the Claude artifact Building CDDA-3D. This page is the summary.

The scale of what it was imitating

Measured on a recent checkout of Cataclysm: Dark Days Ahead (raw line counts, blanks and comments included):


C++	~1.0 million lines
JSON game data (items, monsters, recipes, map pieces)	~2.0 million lines
Commits	~130,000, since October 2010

The first night


Human input before v1	one prompt and four multiple-choice answers
Prompt → "finished"	5 h 26 min
Subagents in that run	24, in waves: data, rendering, world generation, UI, monsters, crafting, vehicles, saves, NPCs, QA
Output tokens	about 1.37 million
v1 size	~53k lines of TypeScript, 565 tests

The four questions it asked were: which engine (answered: "You pick, note this is NixOS so you can use anything that can be accessed via nixpkgs"), what Project Shadowglass is (research it yourself), whether to import the game's JSON directly (yes), and how much autonomy to take (go big, many hours).

Four weeks later


TypeScript	~168k lines
Tests	2,325 passing
Subagent runs	148, about 287 agent-hours
Messages typed by the author	139, across 20 lead sessions

The live version switched from Dark Days Ahead to the Cataclysm: Bright Nights fork and gained a mouse-first interface aimed at players who bounce off the classic keyboard menus. Additions since include walkable stairs, riders on bikes, sewers, subways and labs down to ten levels underground, rag-doll run-overs, and distant buildings that no longer pop in while you drive.

Bright Nights and Dark Days Ahead game data is CC BY-SA 3.0, © their contributors, and so is the UltiCa tileset by its authors. Images derived from them are shared under the same licence.