Here is the full list of all 39 Nex Machina achievements.
Clear a single world while succeeding in every end-level minigame on any difficulty
Complete a single world on Experienced difficulty without saving any humans
Succeed in 10 end-level minigames in a row on any difficulty
Earn 3 bronze medals in the Arena
Beat Machine City on Experienced difficulty in under 5:45
Complete Techno Forest on Master difficulty
Complete Arcade mode on Veteran difficulty
Complete Arcade mode on Experienced difficulty without continuing
Clear a single world on Experienced difficulty or higher without getting hit
Dash through 3 beams with single dash
Deal a killing blow to a boss with a Sword attack
Complete Techno Forest in arcade mode on any difficulty
Complete Crystal Mountain in arcade mode on any difficulty
Complete Fire Caverns in arcade mode on any difficulty
Complete Machine City in arcade mode on any difficulty
Complete Future Labs in arcade mode on any difficulty
Complete Space Station in arcade mode on any difficulty
Complete Arcade mode on Rookie difficulty
Complete Arcade mode on Experienced difficulty
Discover a secret level
Save a human while it's being harvested
Complete a feat
Reach a human combo of 5
Fully power up the Hero
Kill a Disruptor
Kill every Disruptor in a single world
Complete all achievements
Destroy every Secret Beacon in a single world
Defeat the Beamtron on Experienced difficulty with one or more enemies still alive
Finish a level without firing your primary or your secondary weapon
Finish 5 levels in a row without movement, dashing allowed
Save all Secret Humans in a single world on Experienced difficulty or higher
Save all Humans and Secret Humans in a single world on Veteran difficulty
Complete 50 feats
Complete 100 feats
Reach a human combo of 50
Reach a multiplier of 50
Earn 6 silver medals in the Arena
Earn 9 gold medals in the Arena