SpaceChem by Zachtronics

SpaceChem is an obscenely addictive, design-based puzzle game about building machines and fighting monsters in the name of science!
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.