GTA: London 1957, GTA and GTA 2. Squash some peasants, look how much blood... Not to mention GTA 3, 4, VC, SA...
Return to Castle Wolfenstein, one of the best games i`ve ever played, bloodiest too.
Soldier of Fortune 2: Double Helix, Maybe not the bloodiest, but they do have destructive bodies...hmm
Dark Sector, Blood splashes like crazy, it`s a bit of nonsense actually...
Now that i think of it, Clive Barker`s: JERICHO, I was astounded by that game, it`s just pure win in my list, and it`s prolly the bloodiest game ever, check some screenies from it, especially Crusade chapter, what do you think you`re walking on?