All weapons
Get all gold in the missions to unlock a bonus mode that gives you all weapons in the game.



Home runs
Find an enemy worm standing fairly close to the edge of the level. Use the baseball bat to hit him into the water to get a "home run" complete with baseball bat cracking sound, baseball message (like "It's Outta Here", or "Bases Loaded"), and organ music.



Bonus Scheme 1
Complete all training modes with at least a Bronze rank to unlock "Bonus Scheme 1" in multi-player mode.



Cool As Ice level
The ice mission near the start is easier than it looks. Collect as many crates as possible without using any utilities, then use the jet pack to get up to the next section near the guard. Collect all the crates there and stand on the polar bear's head. Point the flame thrower at a spot just to the left of the guard, and fire. You should get through the barrier protecting him, and the flames should send him into the water.

Walk forward until you get both the uzis, then jet pack over onto the polar bear. Grab the battle axe and shoot the next closest crate with the uzi, standing back to avoid damage, to blow a hole giving you access the area where the Guard worm is. Use your other jetpack to go behind him then blast him into the water with your other uzi.



Pumpkin level
On your first turn, use the laser sight and shoot the oil barrel with the shotgun. Kill two snipers with your first shot gun shot, then kill the last sniper with your last shotgun shot. On your next turn use the ninja rope to get to where the first crate is located. It contains a baseball bat. Whack the enemy in front to kill him. In the next turn, get past the mines by with ninja rope or some other method. Then proceed to the special crate and take it.



Super Sheep Racing
If you have collected a crate at the very left of the level, and the next crate appears at the very right, deliberately crash or detonate your current sheep and set off a new one. This will save time.



Desperation attack
If you are almost dead and a lot of worms are nearby, use the Banana Bomb to blow them all up.



Ignored by CPU worms
Have your worm stand on its head. Unless a CPU worm has the next turn, it will not be shot. The CPU will not intentionally lose one of its own worms in order to kill one of your own.