Are you looking for online multiplayer experiences or single player?

There are many games that don't involve killing at all.
And there are games where it's possible but not mandatory to kill humans, that always let you choose how to interact with NPCs.

What genres do you prefer?

I love open world games. I'm not so good at strategy rpgs, but ill pretty much give anything a try. In repley to FrazerJC, I don't really care which.

These are my favourite games I played in 2012 that don't revolve around fighting:

Adventure:
Blackwell series
Broken Sword series
Monkey Island 1+2
Primordia
Syberia
The Longest Journey

Business simulation:
Football Manager 2012/2013
Patrician III
SimCity 4 Deluxe

Puzzle:
Audiosurf

Strategy:
Blood Bowl

Orcs must die?

Originally posted by Satoru:

Orcs must die?

Maybe it's not cruel to humans but think about the poor orcs, why all this hostility towards orcs. :P

I'm not sure if you mean your character not killing humans or no one in the game killing humans, but technically your character in Batman Arkham Asylum and Arkham City doesn't kill anyone; he always knocks them out. It has a really nice open world feel to it. On the other hand, the NPC aren't so nice...

Worms

Alice: madness returns maybe? Dark Souls has you fighting undead not people, and has a pvp/multiplayer aspect to it too. both of those are excellent games :)

Originally posted by bblacrosse123:

My parents won't let me play any games that involve killing humans, but they will allow killing other fictional creatures (aliens, monsters, etc) What games are good, but don't involve killing humans?

I think Terraria doesn't involve killing humans, though te closest things to them are zombies. But I haven't played it enough to the full extent.