You're playing Agony The Portal
Description
The Authors of this game contacted me directly to add this one, after checking it out I almost didn't because I didn't see a relation to Zombies. The Authors then provided me with this description which made it seem ok.
You play an undead lord who just escaped out of his tomb and is now about to slay the kings of Gonia, to reunite with his (undead) brethren (The outro is about the player opening the gate to the realm of the dead and the other undead kings come out ). Hence you don't shoot zombies but you are one. Similar to the Sonny setting where
you play a zombie and fight against living creatures.
You play an undead lord who just escaped out of his tomb and is now about to slay the kings of Gonia, to reunite with his (undead) brethren (The outro is about the player opening the gate to the realm of the dead and the other undead kings come out ). Hence you don't shoot zombies but you are one. Similar to the Sonny setting where
you play a zombie and fight against living creatures.