Mortal Kombat 1 creative director and franchise co-creator Ed Boon is teasing fans on social media once again, this time about possible Kameo fighters that could be added in the new Khaos Reigns expansion. The biggest addition to Mortal Kombat 1s gameplay is the Kameo fighter mechanic, which allows players to select a secondary supporting character from a separate roster to help in battle. These Kameos are mainly pulled from the classic Mortal Kombat timeline and can be called into the fight with a button press, opening the door for all kinds of new attack combinations.