As one of the last humans alive, you need to love you some zombies to save the human race. Revive zombies and help the un-undead escape thru the portal. Since zombies love beating hearts, distract them with yours.
A rift in spacetime has resulted in a large number of World War II era planes getting stuck on the world snake.
Join the frequent fliers club of Ouroboros Airlines, racking up points while taking advantage of the torus nature of your new environment.
Hubert runs a park with the allegedly extinct dodo. You have gotten a pass to go hunting on his lands. Kill as many dodos as you can in the time limit. The higher your score the more money you have to spend on new weapons.