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 3 Red Dudes with one rifle burst.
Kill 100 Red Dudes with a rifle.
Kill 100 Red Dudes with a katana.
Cut bullet with a katana.
Complete the game.
Kill 100 Red Dudes with a shotgun.
Score 100 headshots.
Get back to the system after being expelled.
Kill an enemy by jumping on him.
Kill 100 Red Dudes using melee.
Upload a replay on killstagram.com
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.
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.