Mortal Kombat (along with Street Fighter 2) is one of the games responsible for the Arcade Revival. It became one of those games people dumped quarters into because of one thing, fatalities. Once it was ported to genesis it basically became one of the first game that your mom didn't want you to own. (along with Doom)
The series as a whole is popular, at least the name is. But a lot of casual fans of the game are 16biters or newer MK9 converts.
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Chrono1219