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