Have 10 Grenades in your reserve
Rescue 10 prisoners in one stage
Score more than 10,000 Points
Clear Stage 3-1
Clear Stage 1-1
Kill 10,000 enemy soldiers... okay, just 1,000
Rescue 30 prisoners
Score more than 50,000 points
Rescue 80 prisoners (there are around 25 per levell)
Clear Stage 3-2
Clear Stage 1-2
Score more than 100,000 points
Score more than 250,000 points
Collect a radio and fly to the next level
Show that 7th digit who's boss by scoring 1,000,000 points
Collect a grenade upgrade
Rescue a P.O.W.
Collect a super grenade
Clear Stage 3-3
Clear Stage 3-4
Clear Stage 4-1
Clear Stage 4-2
Clear Stage 4-3
Destroy the enemy army and beat the game (no cheats)
Clear Stage 1-3
Clear Stage 1-4
Clear Stage 2-1
Clear Stage 2-2
Clear Stage 2-3
Clear Stage 2-4
Collect a pair of binoculars
Collect a bulletproof vest
Collect a machine gun power up