From 1 to 5 (5 being the worst).

5. (HORSES) All Total War games

Something this game does that very few games do, is show animals as the casualty of war. Aside from seeing piles of human bodies after a battle, horses are piled along side them. Panicking riderless horses wander aimlessly on the battlefield.

4. (not sure what to put)

3. (CHICKENS) Crysis

In Crysis the player can use the nano suit for increased strength and kill both chickens and enemy by throwing the chicken at the enemy face. The player has no interaction other than throwing the chicken.

2. (DOG) Fallout

In Fallout dogs are both vicious and kind. In this game you not only kill dogs, you eat them afterwords. While in some cultures eating a dog isn't really a problem, it's interesting seeing how you can become attached to one, then eat it after it has died. This is fucked up, to a degree.

1. (PIGS) Rome: Total War

In Rome: Total War you set pigs on fire with oil and send them burning alive screaming at the enemy to scare them. The pigs in this game serve no direct combat purpose, they are used a moral mechanic with the only purpose in the game to be burned alive. The enemy can also kill them while they are being burnt alive. Apparently this is what actually happened.