I'm afraid to post ideas because it requires me to strongly commit to something. But I don't think anyone will share my effort, making any possible attempt to do so, be in vain. >.< Also I actually tend to have thought out/explained RP's while also lacking in a bunch of direct rules and some of my ideas which I've successfully done with friends, would go absolutely nowhere on this forum. But I will give one in particular that I simply love doing, despite it's many variations I've done.

An RP where controlling other peoples characters, with very minimal warning and limits, is nearly the entire point/plot. 

I've done this as a psychological thriller where all characters we're unaware but fully sentient puppets, where the GM would outright manipulate actions. No word, no confirmation. Often through characters giving the GM their written paragraphs and the GM changing them ever so slightly. It was so damn fun, because it sort of became "The Thing" in RP form in a way. (least the first run, second one was a little different and would take longer to explain than I feel like typing.)

Only did this one once, an action battle themed one with sentient robots that want a life away from their slavery, starting a revolution to kill their special human creators, where the human's only real advantage was having small windows of controlling their actions for a brief moment of time. Getting brief seconds of control time or something along those lines. Making for some pretty fast paced an actual strategic fights.

Would love to do something like that again. But yeah, I wouldn't dare waste my time if it would die as quickly as most of my RP's tend to do.

Oh, I also adore doing very dark themes for certain anime/cartoon shows styles, with people not being afraid to die or get injured and punished. But I see so many conversations about how people dislike RP's like this. So I wonder if I'd ever get enough interest in the first place.