Bonus level:
Successfully complete story mode to unlock the bonus "Infinity" level.

Blast Helm:
Defeat the Infinity level 50 Boss.

Inferno:
Defeat Colossus (Sector 2 Base Boss).

Judgment:
Defeat Enforcer (Sector 2 City Boss).

Neutron Gun:
Defeat the Infinity level 30 Boss.

Onslaught:
Defeat the Infinity level 10 Boss.

Surge Helm:
Defeat the Infinity level 40 Boss.

Trident:
Defeat the Infinity level 60 Boss.

Vulcan:
Defeat the Infinity level 20 Boss.

Quick reload:
Start to reload then switch to a different weapon. Switch back and your weapon
will be reloaded about three times faster.

Weak spots:
For the three Bosses in Sector 2, their weak spots are as follows.

Enforcer (City Boss): On the machine's back near the bottom, is a circular lighted
area. Your crosshairs will lock on to that area. Shoot it with a shotgun or rocket
launcher for best results.

Colossus (Base Boss): Climb the stairs until at the very top and look down at
Colossus's head. When the head opens, shoot it with a shotgun for best results
(1/5 to 1/4 damage).

Mantis (Ruins Boss): Get close to the bug and shoot the underside. Shooting its
shell will not do anything, as it deflects most of the shots. The best weapon is the
Photon MG because it stops Mantis in its tracks.