Unlock Bonus Level

Finish the game once.

Unlock Inferno

Defeat Sector 2 Base boss - Colossus.

Unlock Judgement

Defeat Sector 2 City boss - Enforcer.

Unlock Neutron Gun

Defeat the boss on Infinity mode level 30.

Unlock Onslaught

Defeat the boss on Infinity mode level 10.

Unlock Trident

Defeat the boss on Infinity mode level 60.

Unlock Vulcan

Defeat the boss on Infinity mode level 20.

Unlockable: Blast Helm

Defeat Enforcer, the lvl 50 boss.

Unlockable: Surge Helm

Defeat Mantis, the level 40 boss.