Here are some cheats and tips for the game Cannon Spike.
Alternate costumes:
Highlight Cammy and press Up or Down at the character selection screen.
Gallery Art option:
Successfully complete the game under any difficulty setting as various characters
to unlock the entries in the gallery option.
Mega Man and B.B Hood:
Successfully complete the game as any character under any difficulty setting. Press
Left or Right at the character selection screen until Mega Man and B.B Hood appear.