Here is the full list of all 11 Crispy Chicken achievements.
Incinerate 25 enemies using a flamethrower
Blast 15 enemies with a bomb
Penetrate 12 enemies with a lightspear
Kill 25 enemies using a shotgun
Get on a 33 kill streak!
Get on a 15 kill streak!
Complete every stage with 100% of the chicken left!
Complete every stage with at least 75% of the chicken left!
Complete every stage with at least 50% of the chicken left!
Unlock all stages!
Finish one level in 2 players mode in campaign