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