Has anyone ever attempted to make a advanced RP that is a multiverse jump-in?

Since jump-in role-plays I always found appealing but they usually are only in free or casual. Never in NRP or advanced.

Is it just not appealing to most people who write on the page-per-post (500/1000+ words per post) level? Or is it that the subject member just doesn't appeal to the type of people who do advanced RP?

I ask since it would be cool to have a multiverse RP where you couldn't use fandom content to see just how far collective on the fly creativity can take a story.

I think the problem is that, once you are dedicating that much detail to an RP (you can write a sentence or two in five minutes, but if you are going to get 500+ words it can take you thirty minutes or more. It takes me a few days to write posts most of the time, for instance), you want to make sure everyone involved can keep up with the subject matter, and that means apps.

A Jump-In Roleplay is like a gathering at a local party or club. You've gone there with some friends that you've called up and told them to come out. While you are there some other friends, or friends of friends happen to be there and it becomes a sort of mix of a few different social group. You may have been the one to suggest the venue but because you are there with so many people you're not really in charge of anything.

A Roleplay where you have to apply is more like a catered event with Free/Casual being a private function with some drinks and food, and Advanced being a 5 course meal with a musician playing in the corner of the room.

Now imagine opening the doors of a catered, 5 meal, private function, to the public and allowing everyone to join. It might go well, but there's always the chance that there is that one guy that can really screw things up, make a mess, has to be asked to leave, and then you have to clean up the mess he left.

It'd take the right player crowd and concept, but there's nothing that says "this is impossible to do". We think the chances of doing it with high rate of success in a multiverse RP is lower than the chances are in a single-universe RP. We think such might require a few rules on things like "How powerful can characters be?" and "What is acceptable to do", but it should most certainly be possible.

As for the time to write advanced length: we wrote about 500 words earlier today in less than ten minutes, and that wasn't story-form. When we get into a character and start writing, it takes way less time to write story-form.

I'm of the mind that they exclude each other in most cases.

Big problem I see with the idea of a jump in game in Advanced or NRPs is that without a character sheet, you can't really be sure if everyone's on the same page and the GM won't know if there's significant things about the character that needs to be addressed until after the game starts. Even in Advanced RPs, I usually get one or two character sheets that just aren't up to standard for various reasons, including the character being super overpowered, being a total Sue, the back story being inappropriate for the kind of game, the player didn't read anything about the OOC before running off to the skeleton, et cetera. In Free and to some degrees Casual it can work because standard are usually more lax and especially in the case of free, character sheets are already pretty much non-existent, so I've noticed that GMs tend to prefer dealing with poor fit players well after they've joined, which is a lot easier when you aren't doing a lot of world building and every character can have a huge impact on the story.

I'm not saying it wouldn't be worth a shot, but don't be surprised if the post length, quality, and character standards are all over the place to a much higher degree than the other sections.