Here is the full list of all 27 Super Dungeon Bros achievements.
Defeat Duke Spookem
Defeat Frost Queen
Defeat Cult Overlord
Have the top score in a 4 player online game
Reach Duke Spookem for the first time with any weapon
Play the game with every weapon
Complete one mission
Complete all of a day's missions in one run
Play the game with every hammer
You played the game with every crossbow
Play the game with every sword
Play the game with every wand
Kill five enemies with a pot
Kill an enemy with another bro
Complete a dungeon with each kind of weapon
Complete a dungeon without dying
Play the game wearing any helmet
Complete a dungeon with everyone having the same type of weapon
Throw all bros over a ledge in one game
Be the only bro alive when everyone else died
Stay alive in threat level 5 for 30 sec
Beat a level before you reach threat level 3
Complete 10 missions
Complete all missions
Kill 10,000 bonies
Kill 7,500 bunnies
Kill 5,000 wasps