If you want to recreate the excitement of a good boxing match, this is your go-to game.
First up, you need a boxer character. A system conbining some die rolls and some free choices let you design a boxer in terms of strength, stamina and fighting style. Then you... well, fight. You can fight boxers generated by other players or there are a whole bunch of pregenerated ones against who you can fight using the rules (which provide for 'automating' boxers when there isn't a player controlling them) - so this game works whether you are on your own or playing with friends.
The whole match is controlled by die rolls, mostly against tables. These cover manoeuvering around the ring as well as the chance of landing a blow and the results of each move. There are two levels of detail that you can choose from, depending on whether you want a blow-by-blow account of your fight or are more interested in just who wins. There's even a table to work out the judges' decision, should a knock-out not occur. And the winner gains Fame which, amongst other things, determines who he will fight next.
For those who want more, there are optional rules for training boxers and for being a fight promoter - running a stable of boxers and managing their careers.
Oh, and if you want, you can always use these rules to moderate a boxing match that the characters in a role-playing game get involved in, or even just go to watch. It's a specialised ruleset for boxing matches, use it whenever you please!