Painkiller: Overdose is the second expansion pack for Painkiller, developed by Mindware Studios, and was released on October 30, 2007. Mindware originally intended to release it as a mod, but DreamCatcher Interactive granted the project full financial and technical support.
It feature 40 types of monster, 6 new weapons, and 16 new levels.
The player takes on the role of Belial, a half-demon, half-angel. Rejected by both Heaven and Hell, Belial was imprisoned by Samael and Cerberus, the locks to his prison bound to Lucifer's very life force.
However, when Daniel Garner kills Lucifer at the end of Painkiller, Belial is released from his imprisonment, and seeks revenge against Samael and Cerberus for imprisoning him.
To do this, he fights his way across hell and, later, Purgatory, battling damned souls along the way.
Eventually, he manages to kill Cerberus and defeat Samael in combat. While he cannot kill Samael, he instead cuts his wings, effectively trapping him. Though he believes he should feel satisfaction, he senses that Daniel Garner needs his help, and sets off to find him, claiming that there is: "no rest for the weary".