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