MudEngine Part 2: Single-Player REPL
What is a MUD?
MUD stands for Multi-User Dungeon (or Multi-User Dimension). These are text-based virtual worlds where players read descriptions, type commands, and interact with the environment and each other — all through a terminal.
The first MUD was created in 1978 by Roy Trubshaw and Richard Bartle at Essex University. Since then, the genre has evolved into hundreds of worlds, some running continuously for over 30 years.
MUDs never went away. Hundreds are still active today, maintained by dedicated communities. They are a fantastic reference for game engine design — every MUD has to solve the same problems: parsing commands, modeling a world, managing state, and describing it back to the player in text.
- Rooms — discrete locations in the world, each with a name and description
- Exits — connections between rooms (north, south, east, west, up, down, etc.)
- Mobiles — NPCs and monsters that roam the world
- Objects — items that can be picked up, used, or worn
- Commands — typed instructions that the engine parses and executes
Most MUDs use a client-server model: a server hosts the persistent world, and players connect via Telnet or a dedicated client. In this workshop we build a local single-player REPL — the game engine runs in-process with no networking.