Enter the Konami Code on the title screen
Clear Stage 1: Jungle
Clear Stage 2: Base #1
Clear Stage 3: Waterfall
Clear Stage 4: Base #2
Clear Stage 5: Snow Field
Clear Stage 6: Energy Zone
Clear Stage 7: Hangar
Clear Stage 8: Alien's Lair and beat the game
Destroy every turret in Stage 2
Move around and avoid the Stage 6 boss without shooting
Defeat the Stage 2 boss without destroying any projectiles, turrets, or using the Konami Code
Destroy every turret in Stage 4
Beat the game's second loop
Defeat the Stage 1 boss using the Laser without jumping or shooting diagonally
Beat the game without crouching - only allowed in Stage 6 to drop through the platforms
Reach the boss in Stage 1 without shooting or dying
Reach the boss in Stage 3 without shooting, dying, or using the Konami Code
Kill 10 Gunners in Stage 6 without damaging any other enemies or using the Konami Code
Defeat the Stage 3 boss without damaging its arms, jumping, or using the Konami Code
Defeat the Stage 4 boss without destroying any of its projectiles or its turret
Let the Stage 5 boss teleport 7 times without destroying any of its projectiles
Defeat the Stage 7 boss while staying on the left edge of the screen and not destroying its mortars
Defeat the Stage 8 miniboss without shooting diagonally
Beat the game without collecting any weapon powerups or using the Konami Code
Beat the game without using the Konami Code
Beat the game without dying more than twice or using the Konami Code
Defeat the Stage 2 boss without damaging any turrets or using the Konami Code
Reach the boss in Stage 6 without shooting or using the Konami Code
Beat Stage 1 without pressing left or using the Konami Code
Enter and clear Stage 4 using only the Flame
Crouch on top of one of the spiked walls in Stage 7
Reach the Stage 3 boss without pressing Up, Down, or using the Konami Code
Collect every item in Stage 5 without dying
Enter and clear Stage 7 using only the Laser
Defeat the final boss without damaging the aliens or their spawners
Get zapped by the barrier in Stages 2 or 4
Score 750,000 points without using the Konami Code
Beat the default high score of 20,000 points without using the Konami Code
Clear Stage 1 without falling into the water