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