Omniversal Gladiator System.

MC owns a multidimensional gladiator arena where he can pick many characters to be gladiators to fight each other with people from the modern world watching it with their souls/minds being transported to seats to watch the fight. Characters who die in gladiator events do not truly die. Both parties get rewarded either in currency or abilities currency mostly for the losers (currencies can buy abilities). There is also a betting system. There is a management system as well with funds in it (MC cant use these funds for himself only able to use to expand his arena by buying or creating different settings or using to support employees or giving compensation to gladiators after matches etc). Currency is earned by bets or people exchanging money into currency to buy access to exclusive matches or any type of merchandising MC gets a certain cut (small) while the rest goes to his management systems funds or employees/gladiators.

Preferably no harem nor romance with gladiators or employees as that will also 100% lead to favoritism.