It's weird to me how much SF6's plot is reminding me of the idea I had for my own fighting game series.
It was about a fictional small island nation in the South China Seas(like a Singapoor analog), where every year, there's a martial arts tournament held, and the winner becomes Emperor of the nation for the next year. And for the last decade or so, the ruler has been an Akuma-type(or, more accurately, an "Augus from Asura's Wrath"-type), who doesn't care at all about running the nation, and is only Emperor because of the thrill of the tournament fights. As a result, the capitol city of the nation has become a beacon of crime and corruption(like Madripoor from Marvel) where the wealthy and powerful can operate without restraint and crime syndicates and corrupt officials control the city, and the entire city has a cultural obsession with fighting and martial arts, for obvious reason.
People from all over the world come to compete in this tournament every year, and your main characters would be the students of the previous Emperor from a decade before, who was a much wiser, more involved ruler, and a great martial arts master, but who was physically crippled in his fight with the current Emperor, and can no longer fight himself.
The tournament, and the game, woulda been called Emperor's Fist. As you can see, it would have had both the "win the tournament, rule the small nation" aspect of Nayshall and also the "Battle City"-like aspects of Metro City in SF6.