Also, same with the Skyrim/Oblivion and mods.

5. You probably never heard about it - Soldier of Fortune 2 with the "Real Fortune Babes" mod. Gore in this game is pretty complex - you can even destroy a few head bones and left the others. Not mentioning shooting the limbs off with the overpowered shotgun or M-60. Different weapons do different visual damage, you can even shoot the window to cut your enemies with broken glass. There is a lot of agony animations. And this mod changes every enemy in the game to female.

Also, this game is a pretty generic military shooter, but the unique gore system itself may keep you going through the main story, randomly generated missions and various map mods.