Here is the full list of all 30 Death Skid Marks achievements.
Finish the game and get the good ending.
Bring the alien to the concert.
Bring the horse to the concert.
Bring the hippie to the concert.
Destroy the brain groupie.
Destroy the groupie from outer space.
Destroy the Clowns.
Destroy one of the tank groupies.
Destroy Jenny5.
Destroy the saw groupies.
Destroy the landcruiser groupies.
Get all other achievements.
Kill 25000 people in all games combined.
Finish the game and get the bad ending.
Finish the game and die for their wins.
Finish the game and get the very bad ending.
Unlock by seeing all four main endings.
Bring the punk to the concert.
Bring the bear to the concert.
Bring the rager to the concert.
Bring the black metal head to the concert.
Bring the emo to the concert.
Bring the goth to the concert.
Bring the gimp to the concert.
Bring the terminal patient to the concert.
Bring the veteran to the concert.
Bring the hobo to the concert.
Bring the wrestler to the concert.
Bring the road warrior to the concert.
Bring the street worker to the concert.