Orcs Must Die is a third person, action, tower defense game. You play as the War Mage, who's job is to kill Orcs, often in rather comical ways. In each level, the Orcs will spawn in waves and try to enter the rift and it's your job to kill them. This done via laying traps, using weapons, or placing guardians to fight by your side. After each level, you will be given a new power to use and skulls based on how well you did; the less Orcs that make it through the rift and the faster you do it, the more skulls you earn. These skulls can then be spent on upgrades for your traps and guardians.
After many hours of gameplay and tens of thousands of Orcs slain, I can safety say that this game IS FREAKING AWESOME. I've sunk about 45 hours into this game (counting the dlc missions). Let that sink in: 45 hours of gameplay! There are triple A games out there that give a fraction of gametime with several times the cost. It's a steal, esspecially if you can get on sale.
However, this game is about exactly one thing: killing Orcs. Beyond that, there's really nothing else to do, but for its price, its a hard deal to beat. If your own the fence, try the demo or watch some clips on youtube. And if you like what you see, buy it. Especially if you can get the entire series bundled and discounted.
Disclaimer: No Orcs were harmed in the writing of this review. Harmed before, oh hell yes!