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