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