Here is the full list of all 15 Operation KREEP achievements.
Killed 5000 "KREEP-lings".
Kill the KREEP when "KREEP eats people" and "CHAOS KREEP" mutators are set! "No sudden death" is not allowed...
Tutorial completed.
Died during the tutorial.
Kill 1000 players!
Kill two players with your exploding corpse!
I used to think I was indecisive. Now, I'm not sure... Kill 10 players and 100 "KREEP-lings" in one match!
Kill 5 players with 5 shots!
Kill two players with one bomb!
Kill yourself 100 times!
Kill 9 "KREEP-lings" with your exploding corpse.
Kill two players with one rocket!
Play a full match with all the mutators activated!
Try all mutators!
Play a match in which your shots never miss a "KREEP-ling" or a player.