Screeps Is An MMO RTS For Programmers
Most programming games aim to abstract or simplify the process of writing code such that it becomes accessible to laymen. Not so Screeps [official site], which bills itself explicitly as an MMO RTS for programmers. That's because all your units - called creeps - are directed via actual JavaScript code you write yourself. It's currently available in early access and it's quite fascinating.
Your JavaScript tells the creeps to do everything from move to attack to trade to build. Because it's an MMO, it takes place on a single server populated by every other player and their army of creeps, and when you log off, your population continues buzzing away with whatever task you set them.
The result is a game where you're pitting your programming prowess head-to-head with other people, seeing who can think of the most efficient methods of completing tasks or imagine new ways to defeat enemies.
A good way to get a sense of this is via the monthly "World Review" posts by its developers, which breaks down current progress into charts, leaderboards and baffling replays. There's also plenty of documentation designed to help you play if your JavaScript is rusty, and 'novice areas' in game where you'll be protected from some of the more dastardly and complex abilities.
Here's a trailer of it in motion:
