you probably need to update the game
You cant the games capped at level 20. However, if you have the Brotherhood of Steel expansion, which can be downloaded, or if you have the Game of the Year edition, which includes all the expansions, the level cap is raised to 30.
in order to play lost in nightmares you have to complete the story level 3-2
You cant.
You cant
you cant yet
you cant
You cant. Thats in Plants vs. zombies, not zombie farm.
you cant .....
you cant get zombie mode until you beat the game on solo mode
no you cant
You cant, Nazi Zombies is only in Black Ops and World at War
zombies are fictinal. so you cant become a zombie in dead island.