Bonus level:
Successfully complete the game.

Bonus items:
Defeat the indicated Boss to receive the corresponding item.

Blast Helm: Defeat Enforcer. 
Inferno: Defeat Colossus. 
Judgement: Defeat Enforcer. 
Neutron Gun: Defeat the level 30 Boss. 
Onslaught: Defeat the level 10 Boss. 
Surge Helm: Defeat Mantin. 
Trident: Defeat the level 60 Boss. 
Vulcan: Defeat the level 20 Boss.