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