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