Beat a truckload of bad guys on normal difficulty or above.
Beat a bunch of vicious dogs on normal difficulty or above.
Shoot down the helicopters on normal difficulty or above.
Kill the skillful multi-shot flamethrowing guy and rescue the POWs on normal difficulty or above.
Destroy 6 mines on stage 4 on normal difficulty or above.
Beat a truckload of bad guys on very difficult.
Beat a bunch of vicious dogs on very difficult.
Shoot down three helicopters on very difficult.
Kill the skillful multi-shot flamethrowing guy and rescue the POWs on very difficult.
Destroy 6 mines on stage 3 on normal difficulty or above.
Complete level 1 without picking up powerups on normal difficulty or above.
Complete level 2 without picking up powerups on normal difficulty or above.
Complete level 3 without picking up powerups on normal difficulty or above.
Complete level 4 without picking up powerups on normal difficulty or above.
Complete all 4 levels without picking up powerups on normal difficulty or above.
Stab at least 25 enemies by stabbing while laying down on normal difficulty or above.
Stab at least 50 enemies by stabbing while laying down on normal difficulty or above.
Stab at least 100 enemies by stabbing while laying down on normal difficulty or above.
Stab at least 25 enemies by stabbing while in the air on normal difficulty or above.
Stab at least 50 enemies by stabbing while in the air on normal difficulty or above.
Stab at least 100 enemies by stabbing while in the air on normal difficulty or above.
Collect 50.000 points on normal difficulty or above.
Collect 100,000 points on normal difficulty or above.
Collect 250,000 points on normal difficulty or above.
Collect 500,000 points on normal difficulty or above.
Equip a flamethrower!
Equip a rocket launcher!
Equip grenades!
Collect flamethrower, rocket launcher and grenades in same game session on normal difficulty or above.
Collect flamethrower, rocket launcher and grenades in same game session on very difficult.
Complete the entire first stage without climbing or jumping on normal difficulty or above.
Destroy 3 mines on stage 1 on normal difficulty or above.
Destroy 6 mines on stage 2 on normal difficulty or above.
Kill the canon-launcher operator before he launches a canonball on stage 1 on normal difficulty or above.