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