Finish Stage 1.
Finish Stage 2.
Finish Stage 3.
Finish Stage 4.
Finish Stage 5.
Finish Stage 6...?
Defeat the true final boss and finish the game.
Finish the game on Hard difficulty.
Finish the game with 2 (or less) Shield Capacity (change in the options menu).
Reach Level 2.
Reach Level 3.
Reach Level 4.
Reach Level 5.
Earn an extra shield by gaining a level at Level 5.
Have 5 Shields at Once.
Go from Weapon Level 1 to 5 using only the Vulcan.
Go from Weapon Level 1 to 5 using only the Laser.
Go from Weapon Level 1 to 5 using only Atomic.
Go from Weapon Level 1 to 5 using only Homing.
Go from Weapon Level 1 to 5 using only Explode.
Go from Weapon Level 1 to 5 using only the S. Laser.
Go from Weapon Level 1 to 5 using only the Photon.
Go from Weapon Level 1 to 5 using only the Grenade.
Try out all 8 weapons in one session.
Try out all 3 speed settings and both satellite formations you start with.
Try the Shadow and Homing satellite formations (unlockable at higher levels).
Earn a score of 1 million.
Get a Secret Bonus (finish a stage taking no damage).
Finish the game without using a continue.