Ive never killed my guests in Zoo Tycoon, but one of the very first god games I ever played was Sim Earth, and it drove me nuts to wait until the soil became rich enough for trees, so before putting in any water, I dropped whales on the land over and over again until the soil was ultra rich.
Then I played the original Sims, and I had one house on the block where the Harbingers lived, it looked like the Addams Family house, and there was the neighborhood graveyard in the back where I would trap some sims inside a cubicle and just leave them there until they died and made gravestones.
Because I too am a sick and twisted puppy.
;D