Of all the strategy games that has good side and evil side. 98% of those will have you play the good side, 1% will let you pick side and the other 1% will have you play the evil side :)
One of the most well-known title of the last 1% is Dungeon Keeper series. You will play as a dungeon master out to conquer the world and defeat all the good guys that dare stand in your way :) I must say that I love the torture room the most since it allow you to convert the captured unit to your side (insert evil laugh here)
Anyhow, not many later developers seem to be interested in letting you play the bad guys until Sick Puppies Inc. came along with Ghost Master.
In this game you will be playing as a civil servant type in the afterlife and you have been given a mission to terrorise the populations of Gravenville :) You will command a pack of ghosts or Haunters as they were called in this game. The locations included Sorority house (where else :p), Frat house, and police stations just to name a few. In each mission, there will be ghost trapped there and will be required to fulfill certain objectives to free them and became one of your haunters. The level of difficulty are ranging from medium to downright maddening... Since the faster you can complete the mission, the more gold phalsm you will gain for training your haunters new scare technique :)
The demo is also available at the official sites. So try it if you like to play bad guys for a change :) You might realize something hidden tendencies *evil laugh*