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