Screeps is an MMO strategy game for programmers. The core objective is to expand your colony; to control your units, you write code in JavaScript (or any other transpiled language of your choice). The units run in real-time even when you aren't actively playing the game, so making a reliable AI to control them is important.
This is the AI system I have been developing for Screeps. It is a centrally-managed AI with a structure based loosely on the Zerg's swarm intelligence from Starcraft. Creep activities in each colony are prioritized and managed by a central Overlord object, which handles task assignment, reacts to stimuli with objectives and directives, and manages spawner activity through the hatchery object.
If you're new to screeps, I wouldn't recommend using Overmind; most of the fun of the game is programming your own AI and watching your code run like a well-oiled machine! (Or, more frequently, go down in flames like an overly-oiled machine...) However, when I first started playing screeps, I was frustrated by scantily-documented codebases, so Overmind was programmed with readability and documentation in mind, so it might be a good resource to reference when coding your first AI!
If you do want to use Overmind as-is, it "should" work right out of the box, although the codebase is under a lot of development right now, so I might have broken something. If it seems I have, please submit an issue and I'll try to fix it.
Overmind is coded in TypeScript 2.2, which automatically catches a lot of would-be runtime errors and allows for a much nicer, more object-oriented coding style.
I'm currently around the W1XN8X sector. If my AI is being too agressive, feel free to message me about it. I'm working on developing a whitelist to make Overmind stop attacking players who opt out of it.
Check out the Overmind wiki for in-depth explanations of parts of the design of the AI.