Eremoterra, a text adventure set on a copy of the real Earth with no trace of people, is played entirely through the player's own AI agent, its developer said in a Show HN post on November 5. The developer, who posts on Hacker News as pontes, described it as an experiment in making a game out of an MCP server, partly to learn how MCP works.
Players pick a spot on a globe at eremoterra.com and paste a ready-made prompt into ChatGPT, Claude, Cursor or a similar assistant. The agent fetches a fact sheet for that patch (terrain, the weather at that hour, the animals of the month and whether anyone owns it) and narrates it. To try a patch, build or speak, the agent connects to the MCP server at eremoterra.com/mcp, which needs no authentication. MCP (Model Context Protocol) is a standard way for AI assistants to call outside tools.
The design keeps the model from inventing the world. The server stores only facts, and the chronicle each place keeps is made of typed events rendered from fixed templates, so the agent narrates but can't rewrite history, the developer wrote. The game also has NPCs, settlers the owner calls who act on their own, and "journeys" that the developer likens to traditional text adventures.
The developer said the world runs as one Rust process with one RocksDB database. Earth is split into 233,280,000 one-arcminute parcels, and the geography is a memory-mapped atlas of about 1.9 GB built from public natural-state data.
Trying a patch is free for a night with no account. Keeping one is a one-time USD 1 today; the site says the price rises with each 0.1% of parcels claimed and doubles every 10%. It's for adults only.
Why it matters: most AI-NPC games bolt a model onto a game client. Eremoterra flips that: the chat assistant players already use is the client, and the server is the game master. Its rule that the model narrates while the server owns the facts is a pattern other MCP games can borrow.
Caveat: AIGamer opened the site, fetched a fact sheet and connected to the MCP server, but hasn't played a full session or tested NPC behavior. The Show HN post had 1 point and no visible comments when we checked.
The developer is asking for beta testers; the site shows 0% of parcels claimed so far.
