Here is the full list of all 26 SUPERHOT achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Kill over 1987 Red Dudes in endless mode.
Unlock all endless levels.
Kill 3 Red Dudes with one shotgun shot.
Find all secrets.
Become part of the community.
Launch every app in the system.
Get RED ending in every level of SPEEDRUNrt challenge.
Get RED ending in every level of SPEEDRUN challenge.
Kill 100 Red Dudes with a rifle.
Kill 3 Red Dudes with one rifle burst.
Kill 100 Red Dudes with a shotgun.
Kill an enemy by jumping on him.
Beat all Challenges.
Upload a replay on killstagram.com
Complete the game.
Kill 100 Red Dudes with a katana.
Cut bullet with a katana.
Score 100 headshots.
Get back to the system after being expelled.
Kill 100 Red Dudes with a pistol.
Kill 2 Red Dudes with one katana throw.
Kill 100 Red Dudes using melee.
Complete SERV level.
Shoot down a bullet with a bullet.
Complete SUBWAY level.