Friday the 13th: Killer Puzzle

Question, you unlocked Death Toll 3: in level 12 of this video, was it random that that happened or should I have unlocked it too, cuz i didn't. right around the 6:50 mark

It is for killing each of the characters, it announces it throughout the game like FINAL SUZI or FINAL CHAD once you kill one of each of the 3 names you will get this one to pop, it is random for the game to give you one of the random characters but once you get all 3 it will pop and with the amount of levels in the campaign it is not missable hope this helps