Screeps World

Screeps: World is an open-source MMO strategy sandbox game for programming enthusiasts. You control your colony by writing JavaScript code that operates 24/7 in a huge persistent online open world. Harvest resources, build units, conquer territory, trade with other colonies. As your influence grows, so does your ability to expand. Multiple players aiming for the same territory may lead to conflict.

The core hook is that you don't need to play constantly. Your units in Screeps react to events without your participation, provided you've programmed them properly. Check in periodically to see if everything is going well. Only basic programming skills are required, but professional developers can push the system to its limits with complex behaviors. Edit scripts from the in-game editor or your favorite external IDE. Other languages are supported via WebAssembly: C/C++, Rust, TypeScript, Go, C#, F#, Kotlin, Swift, D, Pascal, Zig, and more.

Permanent MMO access with a 20 CPU limit ships with the starter package. Unlock full CPU through Lifetime CPU unlock or in-game credit purchases. A standalone CPU-limited world shard lets unlocked-and-locked players compete on equal terms. Host your own server, modify the rules, and play with friends on LAN or internet; the server is open-source. Game pace runs 2-5 seconds per tick for real-time debugging.