Orcs Must Die! is looking mighty fine with its mix of tower defence and hands-on action; a lovechild stemming from a ménage à trois that involved Dungeon Defenders, Sanctum, and Warcraft III if you will.
Because these types of games tend to confuse a fair amount of people, Robot Entertainment has created a series of videos to provide you with an interactive view of what dealing with waves of orcs will play like. Just remember to click a selection when prompted to do so, or it will be a bit of a boring video.
Don't feel too bad about the orcs, though. Other games will one day let them enact their revenge.