Here is the full list of all 50 Mortal Kombat Komplete Edition achievements. It takes around 200 hours to unlock all of the achievements on Windows.
Complete Story Mode 100%
Perform every fighter's forward and backwards throws
Complete Arcade Ladder with All Fighters
Perform a Fatality with all playable fighters
Complete 200 Versus matches (online OR offline)
Complete Arcade Ladder on max difficulty without using a continue
Win A Ranked Online Match without jumping
Win an Online Match
Win Arcade Tag Ladder with robot Sektor and Cyrax
Win 10 Ranked Online Matches in a row
Complete 100 Online Matches
Win 100 total Online Matches
Get a Flawless Victory in an Online Match
Earn 1000 Respect Points via King of the Hill Matches
Unlock 50% of the Krypt
Unlock 100% of the Krypt
Earn 2500 Respect Points via King of the Hill Matches
Win 10 King of the Hill Matches in a row
Perform 8 throws in an Online Ranked Match
Win both rounds with timer running out in an Online Ranked Match
Comeback with under 10% health in an Online Ranked Match
Successfully land every playable fighter's X-Ray attack
Get all MK Dragons in Test Your Luck
Unlock all Alternate Costumes
Unlock Mileena's 3rd Alternate Costume
Gain Mastery of 1 Fighter
Gain Mastery of All Fighters
Complete all Test Your Might mini-game challenges
Complete all Test Your Strike mini-game challenges
Complete all Test Your Sight mini-game challenges
Complete 25 Tower missions
Complete all Tower missions
Perform and land a Tag Combo
Perform 1 of each type of "-ality"
Perform any fighter's hidden finishing move
Perform every fighter's hidden finishing move
Unlock Hidden Fighter "Quan Chi"
Discover and fight Hidden Kombatant 1 in Arcade Ladder
Discover and fight Hidden Kombatant 2 in Arcade Ladder
Discover and fight Hidden Kombatant 3 in Arcade Ladder
Complete Tutorial Mode
Unlock Hidden Fighter "Cyber Sub-Zero"
Complete Arcade Ladder with Any Fighter
Complete Arcade Ladder without blocking (allowed to continue)
Complete Story Mode 50%
Spill 10000 pints of blood
Complete Fatality Trainer
Perform a 10-hit combo with any fighter
Discover and fight Hidden Kombatant 4 in Arcade Ladder
Perform a Fatality!