There've been a lot of good 40K games (surprisingly). The old PC strategy titles were pretty good (but nigh unplayable today, as time marches on). Fire Warrior on the PS2 was pretty meh, but was kind of neat for being a 40K game not centered on the Imperium's perspective. Dawn of War was pretty great and it's expansions were all good, with the exception of Soulstorm that wasn't developed by Relic. Dawn of War 2 is definitely not for everyone, but is pretty enjoyable as a quick playthrough of the campaign (considering, during a sale you can get it and all it's expansions for less than 10 bucks, it's worth it's price). Space Marine is actually a pretty competent 3rd person shooter. It's flawed, but I liked it right up until it's shitty last boss despite it's repetition. The parts where you get to don an assault pack and jump jet around kicking all of the asses were definitely the highlight.