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