In the grim darkness of the near future, there is only this game: Warhammer 40K: Space Marine.
An action title from noted strategy devs Relic, it's about Space Marines. And Orks. And Titans. That should be all you need to know.
Oh, and don't mind the fact that this is a developer diary; it's mostly made up of gameplay footage, so think of it as a trailer with commentary.