Concept art:
To unlock Concept art, at the main menu, hold 1 and press Up two times, Down two times, Left, Right, Left, Right.
Unlockable Characters:
Unlock the following characters by performing the corresponding tasks:
Boogey – Beat Mission 9 in Tier 4 in Mission mode.
Chicken – Beat Story mode with all characters and accumulate 10 hours of game play time.
Dracula – Beat Mission 5 in Tier 3 in Mission mode
Eris – Beat Story mode with Billy, Mandy, Grim, or Irwin
Fred Fredburger – Beat Story mode with Billy, Mandy, Grim, or Irwin
General Skarr – Beat Mission 6 in Tier 4 in Mission mode
Hoss Delgado – Beat Mission 9 in Tier 1 in Mission mode
Jack O’Lantern – Beat Mission 9 in Tier 2 in Mission mode
Lord Pain – Beat Mission 9 in Tier 5 in Mission mode
Mogar – Beat Story mode with Billy, Mandy, Grim, or Irwin
Nergal – Beat Story mode with Billy, Mandy, Grim, or Irwin
Nergal Jr. – Beat Mission 9 in Tier 3 in Mission mode
Nerglings – Beat Story mode with every character
Pumpkin – Beat Story mode and inflict 100,000 damage points
Vikings – Beat Story mode with all characters and destroy all letters in the credits sequence
Alternate costumes:
To unlock an alterate costume for a character, beat Story mode with that character.