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