Diablo 2

If you got through BioShock then this won't even make you flinch. There were 2 parts in that game that REALLY disturbed me.

1) When you listen to the recordings on the surgeon, where he starts operating on someone that's not under.

2) When you listen to the recordings of the person being conditioned to do whatever the "puppetmaster" says. (it involved a dog)

Amazing game though

Although there are many more gruesome games, it sounds like you should wait...