One of the best ways to fight a munchkin as a DM is to keep making their min maxing irrelevant. They get good at fighting, endless block puzzles that reset if they break things. They take super speed, make the city have endless fragile stuff everywhere and have the MC to busy doing odd jobs (slowly) endlessly to pay for all the random stuff he broke. Get out of the starting slums and goes all high society on you... turns out the threat was in the slums and the media wasn't covering it. Have fun trying to use class and diplomacy on the zombie hoard. Giant robot pilot... meet super heavily armored giant rust beast, it flies and teleports. They get too powerful for the system... this attracts epic level encounters.. and as its MC's fault MC gets the fun of paying for the damages.
In short, the GM (unseen or whatever) has the job of making things difficult for the MC. To keep things interesting. To keep the MC involved.
That was the biggest strength of Gantz for me. After getting nothing, but useless fodder the Gantz in charge of that unit get a super combatant with absolutely no interest in participating. The interplay between Gantz forcing the MC to participate and the MC trying to weasel out of things is the best part.
In short, the GM (unseen or whatever) has the job of making things difficult for the MC. To keep things interesting. To keep the MC involved.
That was the biggest strength of Gantz for me. After getting nothing, but useless fodder the Gantz in charge of that unit get a super combatant with absolutely no interest in participating. The interplay between Gantz forcing the MC to participate and the MC trying to weasel out of things is the best part.