Grey Matter is a collaborative project developed by the creators of Goo! and Gish, where players take control of a black dot which can only destroy enemies by running into them. Use the cursor keys to move, hold the shift key to reduce your movement speed, and press the space key to activate your boosts temporarily.

Points can be traded for upgrades in the pause menu, accessible at any time by pressing the P or escape key. A stand alone version is available for download as well, which should run quicker on older machines. (source: Paul Eres)

Name: Grey Matter
Developers: Edmund McMillen, Tommy Refenes, Danny Baranowsky
Category: Arcade
Type: Browser
Size: 5MB
Direct download link: Click here