Multiverse Traveler: Among Worlds

"Having died in an act of bravery, David awakens in Nexus, the point beyond realities. Orion, the administrator of Nexus, offers him a unique opportunity: to help different realities prevent catastrophic events.

Endowed with special abilities, David embarks on his mission, traveling through various fictional worlds to fulfill missions aimed at saving these realities from catastrophic disasters.

In one world, he was a soldier and scientist who created the vaccine for a zombie outbreak.
In another, a priest, a member of an order that fought to exterminate vampires.
And he has also been a brilliant scientist who fought alongside the Autobots."