To unlock mirror mode, finish the entire Story Mode, using only one credit.

To unlock ye olde automatic weapon for continuous use, beat the Story Mode twice.

Complete Story Mode using the Automatic Weapon to get infinite ammo. Woo-hah!

Need some Wide Ammo? Who doesn't? To get it, complete the Story Mode using Infinite Ammo. It's a building process.

To unlock Extra Mode in Shoot Away 2, get the high score in Retro Mode of Shoot Away 2.

Basically, all you have to do to get more credits is to suck horribly. Every time you lose all your credits, an extra is added to your beginning amount the next time you play. After you rack up over nine credits, the game will switch to Free Play.

Beat Story Mode one time to unlock Crisis Mission.

Beat the final mission of the Crisis Mission mode to unlock the music player.