Here is the full list of all 26 SUPERHOT achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Beat all Challenges.
Kill over 1987 Red Dudes in endless mode.
Unlock all endless levels.
Kill 3 Red Dudes with one rifle burst.
Launch every app in the system.
Become part of the community.
Get RED ending in every level of SPEEDRUNrt challenge.
Get RED ending in every level of SPEEDRUN challenge.
Find all secrets.
Kill 3 Red Dudes with one shotgun shot.
Kill 2 Red Dudes with one katana throw.
Kill 100 Red Dudes with a rifle.
Kill 100 Red Dudes with a katana.
Complete the game.
Kill 100 Red Dudes with a shotgun.
Score 100 headshots.
Cut bullet with a katana.
Get back to the system after being expelled.
Upload a replay on killstagram.com
Kill 100 Red Dudes using melee.
Kill 100 Red Dudes with a pistol.
Complete SERV level.
Kill an enemy by jumping on him.
Complete SUBWAY level.
Shoot down a bullet with a bullet.