Here is the full list of all 37 The Slimeking's Tower achievements.
Maiyan Completed
Beat the portal
Reach The Portal
Reach Sigma
Reach Theta
Reach Tau
Reach Ohm
Reach Pi
Midas Unlocked
Reach the basement
Maiyan Unlocked
Jade Unlocked
Igneous Unlocked
Reach Omega
Reach Gamma
Reach Epsilon
Attack a mimic before it's transformed
Reach Delta
Reach Beta
Get your first boss key
Defeat Lodeslime
Play Adventure Mode for the first time
Unlock Hairry's secret item
Dots Unlocked
Mind Unlocked
Void Unlocked
The Collector Unlocked
Prayer Unlocked
Dots Completed
Mind Completed
Midas Completed
Igneous Completed
Void Completed
Jade Completed
The Collector Completed
Prayer Completed
Hairry Completed