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