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