I've been running a rotating GM group for about four years now. There is no obligation to GM, but most people end up wanting to at some point. Really our only standing rule is "no D&D or clones".

We seem to settle into shorter campaigns...6-9 months real time with one exception...and at the end of each campaign two or three guys will set the table with a couple options they'd like to GM. There is completely non-codified process that selects one based on social consensus based on what seems interesting as a setting, GM fatigue/desire, cool systems, and so on.

Then that GM runs it. Rinse and repeat.

I have to say, it works. If I had to say why, here would be my answers:

- Everyone is a bit older and has been gaming for a bit. There's no inherent virtue to age, but it does mean that we made our tragically bad player/gm social contract mistakes in the past.

-Pretty much everyone WANTS to GM something. Specifically a non-d&d something. They have some ideas in their head for a cool story, a system they always wanted to try, a setting that they really want to explore. So GMing is a great way to make it happen, not an unfortunate drudgery to pay for playing.

-The systems tend towards the more mechanically simple. Besides reducing prep and memorization costs, it also helps avoid having to account for an excess of wildly specific and granular player actions with all the social Friction that can cause.

And it's been a blast. A heist in the Mistborn setting. Imperial Guardsmen in Only War. A low fantasy series of swashbuckling adventures. Cthulu in the early days of humanity in space. A kingdom and army level game about a rebellion to overthrow a daemon emperor. Open ended, or with pre-assigned characters, long contuity to a series of thematixky linked one shots, pretty much the gamut.

But I would really stress "you HAVE to run" isn't the point. The point is "you want to run." I've yet to see a campaign end without multiple players immediately volunteering to run a different game.