Personally... I think it should be rated M for Mature. Besides, look at Half Life 2! Penumbra may not fall in the same genre as HL2 does, but it sure is just as realistic!!! I mean come on... Alone in the Dark by Interplay had some blood and guts and that was an adventure game from 1992 and it was kickass as a result of the violence.

Don't get me wrong, I don't like gratuitous violence, but the monsters should bleed a little bit. Those dynamite explosions should tear anything to shreds. Ok.. I'm rambling on here........
Guru