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