Here is the full list of all 21 Action Henk achievements.
Publish a level to the Steam Workshop.
Fall into the lava.
Defeat Kentony's challenge.
Defeat Betsy's Challenge.
Beat Neil's Challenge.
Beat Cedar's Challenge.
Beat Kentinator's Challenge.
Beat Action Henk in the City.
Earn a Bronze medal on all levels.
Earn a Silver medal on all levels.
Earn a Gold medal on all levels.
Earn a Rainbow medal on all levels.
Beat all bonus levels
Challenge a friend to beat your score.
Ragequit the game during a level.
Beat 99% of all players on a level.
Jump over the barrier.
Win a multiplayer match.
Press reset over 9000 times.
Die 100 times.