RAPT is a complex and challenging HTML5 platformer. The exit to each level is blocked by enemies that roll, jump, fly, and shoot to prevent escape at all costs. Gameplay is exclusively two-player and uses a unique split-screen mechanic. The levels and enemies are designed to promote cooperation between players.
RAPT also comes with a powerful level editor which allows players to create levels of any size. Levels are saved to the player's account on the server, which has a public page listing custom levels. Link to this page for a simple way of sharing levels with friends!
Note: RAPT is a physics intensive game and your browser might not be up to the task. For the best experience please use the latest version of your browser.
The game and the editor are written entirely in JavaScript using just the HTML5 canvas API and some jQuery, and the server is written in Rails. Our code base contains a little over 20,000 lines of JavaScript and it's all open source on Github.
Found this gem of a html5 game while doing some research. Control is amazingly smooth, and the whole thing is incredibly fun and polished.
...trying to control both robots at once made my head essplode though. XD