A delightful Space Hulk/Space Crusade/WH40K top-down tactical mash-up. To say they've borrowed heavily from Games Workshop is putting it mildly.

Right down to the weapon combinations (power fist and sword, etc), the light/heavy dice, the genestealers, even the lore of space chapters thousands of years old. They just slightly rename everything.
But... they've ended up making probably the best PC incarnation of Space Hulk/Crusade/WH40K money can buy. It also has a lovely stat system and skill-trees, so you can create very different styles to your squad of Space Marines, er.. I mean Templar Knights. Plus respeccing is free.
If you're in any way interested in this sort of thing I highly recommend it.