Quote:

Sanctum is a first person shooter tower defense where you take the role as Skye, an elite soldier sent out to protect her home town, Elysion One, from hordes of mysterious alien creatures. To succeed you have to construct and upgrade defensive structures. What makes Sanctum unique from other tower defenses is that when the havoc starts, you jump right into the action with your own weapons and play a key role in the defense. Sanctum has taken the best features from first person shooters and tower defense games to create something totally unique.

http://store.steampowered.com/app/91600/

This game looks like it will be a lot of fun. It comes out in just over two weeks. Graphically it reminds me of Defense Grid mixed with Unreal Tournament and Halo.

The game was started as a mod based on Unreal, but it gained enough of a following and support to be its own full game.

http://www.facebook.com/SanctumGame

It also helps that Unreal's licensing deal is is amazing.