Full list of all 50 Mortal Kombat achievements worth 1,000 gamerscore. It takes around 300-500 hours to unlock all of the achievements on Xbox 360.
Win Arcade Tag Ladder with robot Sektor and Cyrax
Complete 100 Online Matches
Complete Arcade Ladder without blocking (allowed to continue)
Complete 200 Versus matches (online OR offline)
Successfully land every playable fighter's X-Ray attack
Perform 1 of each type of "-ality"
Perform any fighter's hidden finishing move
Perform a Fatality with all playable fighters
Spill 10000 pints of blood
Win 10 Ranked Online Matches in a row
Perform every fighter's forward and backwards throws
Win both rounds with timer running out in an Online Ranked Match
Perform 8 throws in an Online Ranked Match
Win 10 king of the hill matches in a row
Win A Ranked Online Match without jumping
Get a Flawless Victory in an Online Match
Win an Online Match
Comeback with under 10% health in an Online Ranked Match
Perform a 10-hit combo with any fighter
Complete Tutorial Mode
Perform and land a Tag Combo
Complete Arcade Ladder with Any Fighter
Perform a Fatality!
Complete Fatality Trainer
Complete Story Mode 50%
Complete Story Mode 100%
Complete Arcade Ladder with All Fighters
Complete Arcade Ladder on max difficulty without using a continue
Win 100 total Online Matches
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
Unlock Hidden Fighter "Cyber Sub-Zero"
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 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
Discover and fight Hidden Kombatant 4 in Arcade Ladder