Why NetherRealm went with a "Kameo" mechanic for Mortal Kombat 1

gamedeveloper.com:

Mortal Kombat 1’s defining new feature is the “Kameo” system, which is an assist mechanic where a character briefly comes into battle to help players turn the tide. They can support players by extending combos or breaking combo chains from opponents. Kameos can even knock opponents out of midair when timed right.

Kameo characters consist of iconic Mortal Kombat characters that have shown up throughout the franchise over the past three decades.

However, the Kameo system looked incredibly different during early development compared to what was put in the final product. Mortal Kombat series co-creator Ed Boon explained to Game Developer how the mechanic took a long journey from drone warfare to a tag team-themed, fanservice-ready feature.

Initially, NetherRealm’s design team approached Boon with the idea that each character would have their own little sidekick—it wasn’t even a person. For example, the military officer Sonya Blade would have a small drone to assist her in fighting.

Boon said that if the game was going to include some sort of assist mechanic, he really wanted to make them interchangeable. In Mortal Kombat 1, every single playable character can team up with every Kameo character. The emphasis was on player choice and variety. He also wanted to do something more with the characters themselves, so the development blended both ideas into what became the Kameo fighters.

Additionally, if the initial concept proceeded as it was, some pairings wouldn’t thematically make any sense. “Why would Kung Lao have a drone with him?” he asked rhetorically. “We really wanted to make the assists a lot more [thematic],” Boon asked. “The main feature I was pushing was that any assist mechanic that we make can be used by any character.”