Robot Entertainment is celebrating four years of game development with a sale highlighting library of releases: Orcs Must Die, Orcs Must Die 2, and Hero Academy.

Purchase of any item from the studio's official store will net you a Steam key to activate the item on Valve's digital distribution platform. Highlights include Orcs Must Die 2 for $3.74 and Hero Academy, with all DLC, for $4.24.

Robot Entertainment rose from the ashes of Ensemble Studios, the Halo Wars developer Microsoft shut down back in 2008. When Ensemble was shuttered, the founders went off and formed Robot Entertainment; others would go on to form Bonfire Studios.