The founder of Age of Empires series of PC games Ensemble Studios that was disbanded by Microsoft didn’t disappear from the scene, instead, they formed a new game studio Robot Entertainment, which soon afterwards announced their brand-new and original series of games Orcs Must Die!. The series currently has published three works in all: Orcs Must Die! (OMD for short) – pure single-player game, Orcs Must Die! 2 (OMD2 for short) – single-player game with double-player co-op game, and Orcs Must Die! Unchained (OMDU for short) – pure multi-player online free game.