OK, I've genned a world and am in the process of setting up a super squirrel secret location for the possible recruited champions to get to. Along the way, they'll be able to amp up their skills and attain a list of kills and whatnot to wow the crowds at the Arena. I imagine that if a PC "manager" continues recruiting heroes and truckin them along to the Secret Arena Entrance (retiring them there), then they could build up a whole stable of gladiators to compete against each other. Best part about this is that multiple copies of the World save file could be played at the same time by multiple Players, so that we wouldn't have to wait for one person to pass it along - The gladiators would be the best of the best from multiple parallel worlds, who step through a dimensional Portal to represent their world Mortal Kombat style...
Of course, the entrance fee for each hero should be an artifact from their world - the hero would have to be carrying it when they entered the Portal, and that would be the prize of the other hero that bested them, (something that still-living heroes could enjoy, until the final winners were living like kings with artifacts surrounding them...)
Just imagine that each manager is one of those "outsiders" that suddenly appear in a world with no history or knowledge of the world around them - it would explain things pretty well if they were like that because they were inter-dimensional recruiters for a multi-dimension hero's challenge...
edit: Each artifact would have to be unique, if one was already used in one world, it would stop being accepted in all the others. The finite nature or artifacts in the world would make the number of heroes able to qualify finite as well. (Unless a hero was able to bring a named weapon or something.)