There was a time when Michael Jackson was the most admired celebrity in the world - then he went a bit nuts. There were people like me that still admired the guy even though it was pretty clear that he was off his rocker. However, I don't think anyone can argue that during the time that this game was released that he was still loved by pretty much everyone.
This game wasn't particularly good as far as the mechanics were concerned, as it was basically just a side scroller where you would kick things into submission. Michael's objective was to rescue kidnapped kids who had been taken by Mr. Big. Apparently this is all based on a movie of the same name from 1988 but I never saw it. I bet it is pretty terrible and I am going to look it up today.
The best part of the game was the soundtrack especially when the screen would fill up with too many enemies and you could activate a "special attack" that would force all the enemies to dance to a famous song that at then end would result in all of their defeat.
This was a major part of Genesis' marketing campaign (which actually worked) where they decided to have games with celebrities on the cover and involved (although probably very minimally) in the production. Most of these were sports games, but Jackson was one of the major representatives for the company at the time.
Sega would spend the next 15 years slowly destroying all the headway that the Genesis made in the console wars.
If you can find a way to emulate this game I certainly recommend you do. This was a piece of history and the game sold extremely well. MJ was always a family friendly type dude so the game is very tame and even though you are killing people, it isn't done in a graphic way. I believe it was shortly after this that Jackson's public appeal started to diminish until his untimely death in 2009.