I'd be in Dark Crusade cutting a swath through the heretical filth with my battle brothers, (Space Marines), chainswording any unfortunate heretic or chaos spawn in half and cutting a swath through the mutant and xeno filth with my trusty plasma gun...at least until I charge with my squad of Grey Knights right into a Greater Khornate Bloodthirster, then I just get picked up, raised over it's horrifying maw of despair, seeing the remains of 1,000 other poor souls that fell to this monstrosity, and feeling the painful squeeze of the Bloodthirster as he squeezes the blood out of me like an over-ripe melon, watching my own life-force drip, no, torrent into it's chuckling mouth, as my battle brothers gaze on in horror, with one last prayer to the God Emperor, I die.
Not exactly the best way to go.
I guess I had better hope that professor's theory on "Game Over" was correct.