Zachtronics Industries is back with an ambitious new design-based puzzle game. Take on the role of a Reactor Engineer working for SpaceChem, the leading chemical synthesizer for frontier colonies. Construct elaborate factories to transform raw materials into valuable chemical products! Streamline your designs to meet production quotas and survive encounters with the sinister threats that plague SpaceChem.

Available for Windows, Mac, Linux and Ubuntu.

You can download a demo for your OS here

(There's a contest over at Jay Is Games with a deadline of March 5, 2011, where you get the chance to win a full game)