Oddly enough, I was just Googling earlier today to see people's thoughts on Zerg vs. Tyranids. Incidentally the overwhelming response is tyranids.
You can actually mod Fallout 3 to wear Ultramarine armour, and a decent bunch of Ultramarines can take out a tyranid fleet, but since you're just in the armour and not one of Guilliman's chosen basasses, I'm not sure it counts.
You can actually mod Fallout 3 to wear Ultramarine armour, and a decent bunch of Ultramarines can take out a tyranid fleet, but since you're just in the armour and not one of Guilliman's chosen basasses, I'm not sure it counts.