So... any other 40k nerds out there besides me? I know a couple people here on XBA have secret mini armies...
You can grab the trial from XBL Marketplace here.
The game is fun but very, very basic. You can kind of tell it was a quick effort on the part of the devs to get a little extra fundage to help their upcoming Space Marine game out.
Coincidentally, you can unlock a special weapon for Space Marine by completing a mission in this XBLA game.
Anyway, it's basically sort of a twin-stick shooter type game but melee attacks also play a big role.
You pick from 4 basic types of Marine: Librarian, Sternguard Vet (who is a Devastator if you play 40k), Techmarine, and a jumppack Assault Marine whose name I forget. You can also choose from a number of Chapters but this is basically just a cosmetic skin change.
Your main weapon type gets upgraded as you get more kills, and you also earn perks you can apply like extra ranged damage or more health. There are arcade-style power-ups you grab like rapid fire or brief invincibility, and overall it's just fun, simple run-and-gunning.
The odd and dumb parts of this game are the glaring lack of online multiplayer, and only 2 player offline/local co-op. This sort of game would be perfect for online 4 player, but oh well.
It's 800 points / $10 and the Achievements seem pretty easy. At this point I would only recommend it to people that are already 40k fans or just complete twin-stick shooter arcade nuts, but I'll post an actual review after I complete all the missions with every unit.