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Unlock all secrets and weapon select in Ghosts N Goblins, Ghouls N Ghosts and Super Ghouls N Ghosts:
To open all of the unlocks in all of the games, hit this code at the Capcom Classics Collection title screen (before you hit start to go to the game select):

L trigger, R trigger, Up Down (on right analog stick), L trigger, R trigger, Up Down (on left analog stick), L trigger, R trigger, Up Down (on cross controller)

If it worked you will get a text message at the top of the screen.

It also unlocks an awesome feature on Ghosts N Goblins, Ghouls N Ghosts and Super Ghouls N Ghosts that gives you access to all of the weapons by hitting left and right on the right analog stick!