Here is the full list of all 12 Worms achievements worth 200 gamerscore. It takes around 8-10 hours to unlock all of the achievements on Xbox 360.
Inflict 20,000 damage
Kill 15 worms using only Sheep
Kill 100 enemy worms
Collect 50 crates
Blow up 25 barrels
Trigger 25 Mines
Kill 3 worms with one shot
Inflict 2,000 damage
Complete training
Inflict 500 damage
Complete all twenty single player deathmatch challenges.
Play a four player Xbox Live game.