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