But I guess, from all the other failed RPGs I've been in, now I know what to look for:
-No complex plot, so I could follow the RP casually
-No RPing over AIM. Entirely journal-based, because for some reason I'm incapable of AIM-RPing now
-Something to drive the game. Even if it's not a plot, I need a reason to keep posting or else I'll quickly lose interest.
-Players are on my flist. At this point I only want to RP with people I'm familiar with, and I don't want it to grow too big.
-Not too busy, but not too empty either. I'm more invested in real life and various fandoms than I was back during Mugenjou, so I have to be able to keep up with an RPG despite that. But if no one's posting, then I'd impulsively come up with something totally random which sounds like a cool idea at first, but later trips me up because I hadn't planned ahead.
Examples: The FMA manga RPG was a lot of fun, but the reason it failed was because we were lacking several important characters (Roy, Scar, etc.) so we couldn't get the plot moving. I'd still like to play FMA manga characters again (like Mei...I would love to play Mei), but in a way that it doesn't stick so close to canon that we have no flexibility. The Pokemon Diamond RPG was also fun, especially to make our characters fit into the Pokemon world, but the problem was that it was difficult to get characters interacting when they were all off doing their own thing.
So...anyone have ideas? I'd even like non-RPers for their opinions, because like I said, I want this hypothetical RPG to be very casual and between friends. No huge commitment, just a lot of fun.