Serious Sam 3: BFE achievements

Decapitate a Khnum.

Complete the campaign in cooperative with at least 2 players.

Earn a medal in Survival.

Pierce 5 enemies with one Devastator round.

Complete the single player campaign.

Complete a deathmatch game with at least 1 frag.

Blow a Major Biomechanoid into pieces.

Use the Mutilator to surf after a Werebull.

Kill at least 3 enemies in one spinning Sledgehammer attack.

Kill 3 enemies in one sprint with the Sledgehammer.

Gib 20 enemies from close range with a shotgun.

Kill 5 Cave Demons while they're in air.