Painkiller: Overdose

Painkiller: Overdose, the third Painkiller game to date, is about a half demon, half angel named Belial. The game adds six weapons, sixteen levels and forty new enemies.
 PC
  CarolinaEN

Overdose was originally a fan mod being developed by "Mindware Studios" in the Czech Republic. The publisher of the original, DreamCatcher Interactive, then gave them full financial and technical support for the project, thus allowing it to be distributed as a full fledged standalone game.

The game also provides the necessary link in plot for the potential proper sequel to the original Painkiller.