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