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