Far Cry 2's storyline is, "in a humanitarian effort to stop a gun-runner in a wartorn African country, you murder just about everybody in that country... largely with guns you bought from the gun-runner."
You realize that whole point of the game is that you're a huge part of the problem, right? The ending is not ambiguous about this.
Buying games you aren't going to play is a waste of money (no matter how cheap they are). Forcing yourself to play games you wish you hadn't bought is a waste of time. Both are best avoided.