“Screeps” is a wordplay for “scripts” and “creeps.” It is an MMO RTS game for programmers in an open persistent shared world. Each player uses JavaScript (or compilers of other languages into JavaScript) to write AI of his or her colony of units (“creeps”) which live and operate in real time even while the player is offline. The game world is generated procedurally and consists of rooms. Players compete for controlling these rooms by mining resources, developing infrastructure, and commanding armies.

Screeps can also be called a sandbox game for programmers since it has no definite goals. Instead, it offers players a fully programmable game world, means to interact with each other within it, and JavaScript API to control game objects. This allows for many possible outcomes for each player and an open-ended nature of the game.