For now at least, the game will be set in the US, with the timeframe being young boxers (19-25 mostly) just turning pro, and entering the pro ranks. The world will consist of (initially) 7 weight classes with 10 boxers in each class, and fighting among themselves for titles in each class.
The default universe will be randomly generated each game (of course there will be options for you to create your own universe with real boxers, trainers, etc. from whatever era you want).
You select up to 3 boxers (1 per class) and control their negotiations for money, their training, and their progress, signing them to contracts that may change over time. Their skills will develop (or not!) as you assign training and manage them, and each boxer will have 8 skills, including Strength, Footwork, Stamina and Reflexes, along with ratings for Jab, Cross, Hook and Uppercut, along with a hidden 'Potential' stat that may dictate how well they develop.
You'll hire a Trainer and a Corner Man to help you manage your fighters of course, with their own set of stats, including Judgement, Wisdom, etc.
This isn't really a 'booking' simulator, as Boxing is somewhat different than Wrestling in this regard. If your boxers do well, the purses will be able to rise up and you'll earn more, and even the right to fight for a title at some stage for big bucks. Injuries, accidents, etc. may happen that can derail a figher's career of course.
Over time, I can add other countries, etc. as demand dictates. The design will be very modular so that expansion of the game will be easy.