I've got a few things that are almost requirements for me to even give a roleplay the time of day, because without them it's almost impossible for me to stay interested in them. I'll just list and explain those.
An established plot. I don't mean there has to be something like "retrieve the magic sword and slay the evil overlord" where the plot is clear and has no deviation, and I don't mean there has to be a specific single goal everyone is aiming for (stuff like "you're all newly created superheroes, survive all the crazy shit that gets thrown at you and work to improve the city" is perfectly fine as an ongoing plot), I just mean that there has to be some actual intent in mind for the RP before it actually starts. I can't stand games that are just like "hey, let's throw all these characters into this setting and see what happens!" They devolve into mindless socializing drivel, all relationship and character building without any actual goals being pursued. I get bored so easily with those kinds of things, because I want to have things for my characters to do other than sit around and chat.
A fleshed out world. Similarly to the above, I can't quite get into roleplays where everything is made up as things go along. I've tried some things where the GM said it was a sandbox world of a particular genre, where it would be built as we explored, but it always felt really poorly crafted and disjointed. I don't mean that there needs to be like detailed maps and bestiaries and history books and so forth about the world to explain every little detail, I just look for the bare minimum to see that the creator has actually thought about the whole of their world and knows what exists in it and how it works. I quite enjoy roleplays where the players have to explore the world to learn about it, but there's a massive difference between exploring an already created world versus a spontaneously generating one. It's kind of the same difference as exists between reading a normal novel and reading a choose your own adventure story; the CYOA thing is an amusing novelty for a bit, but if you want anything with real depth and lasting entertainment value you head for the real novels.
Something that inspires my creativity. This one is extremely nebulous, but it's still important. It could be some game mechanic that I like, it could be something about the overall plot that catches my fancy, it could be some neat idea another player came up with, it could be something special about one of the factions or races or whatever in the roleplay, it could be something neat about how magic works, it could be some neat tidbit about some little unimportant town, or it could be something else altogether. Basically it has to be something that gives me an idea for a character that would be fun to play and that really fits in the world. I never play the same character in two different roleplays, and I like making characters that truly feel like a part of the world, so I'm always on the lookout for something neat to base my new character on for a roleplay. If I can't find something about the world that interests me enough to inspire a character, I just don't bother trying. I've got a fertile enough imagination that if I get through all your given roleplay info and look through all the existing character sheets and not even one thing pops out that makes me want to create a character right there, then it's probably not going to be enjoyable to play in, so screw it.
