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