This. I still don't understand how some company, with all the MMOs we've seen thrown at the wall to date, hasn't come up with an MMO where you farm for rare spawns to capture and level up and use to fight other people in various manners.
Shit would work great, a little ingenuity. You could do arenas, two vs two, open world duels, large scale competitions between pets. Main characters could level up or rank up skills which influence their pet's abilities, the min max and depth that could occur in such a game clearly would be a big draw in the same types of communities that like collectable card games and Pokemon and the like. Throwing ideas at the wall on this could come up with about a million major changes and innovations in the MMO genre it wouldn't even be funny.
The industry is stagnant, that's the only excuse for this not happening already. In fact it kind of has, in a way, on Facebook, in that Insomiac made game, but that's a facebook game and what we'd need in an MMO is a much more fleshed out everything from the Insomniac base game, including a real 3-d world.
Imagine how developers could add rare spawn limited time only mobs and the race to grab them and all that. Shit might be tough to balance but so what?
It would be FUN.
