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