Mini-game:
Successfully complete the game. Then, highlight the "Options" select at the main menu and press X + A + Start.

Hint: Best ending:
Successfully complete the game after saving all your friends.

Hint: Worst ending:
Successfully complete the game after saving none your friends.

Hint: Eriko wearing just her underwear:
Successfully complete the game, then play through again. Do not rescue anyone while playing the game. Eriko will lose a piece clothing with each friend that is lost. Eriko will be in her underwear by level 6.

Hint: Easier time rescuing Michel on level 2:
Get the Flamethrower first, the defeat the Worm Boss. Next, run to the garage and use it against the three Monkillers.

Hint: Hidden Boss battle:
Successfully complete the game, then play through again. Do not save any of your friends during the second game to eventually fight Michael Reynolds.