Oh man, I have a lot of ideas. For an original work, I had an idea of a novel of sorts called Mosaic. It would basically be set in this island called Jericho that is technically within US soil, but is politically segregated from it/isn't part of the US. In the past, after World War II, the island was infested with crime and that gave birth to a lot of vigilantes, so it was total, utter chaos. But then they separated from America and was put under control of RedWatch, a former-mercenary company turned into a legitimate law enforcement. Crime's at an all time low, with organized crime basically non-existing. Technology's a little bit futuristic. And the first part of this novel would be about life in this utopia with hints here and there that something is gonna happen. And then the second act would basically shatter this illusion of a utopia once they are attacked by a terrorist force that were basically operating under their nose, forcing vigilantes to re-emerge and the island to become engulfed into chaos.
I tried to incorporate this setting into a roleplay, but sadly I never could get enough interest even after three tries.
As for fan-fiction, Shinobi Chronicles would be a Naruto fanfiction which would provide details regarding the life of important characters in the series. Most of these would be headcannons while some of them would be stories that I made up. Also, some of them would be one-shots while others would have to be in several parts. It would cover all types of genres; romance n'fluff, action, thriller, slice of life and all of them would be set in the canon. Some of these stories that I was going to put were;
-Third Hokage and Danzo post-World War I, fighting a very skilled puppeteer who attacks Uzushiogakure. I would put more emphasis on Hiruzen's title as "The Professor" by having him use several hiden jutsu.
-One set in the future, where Naruto's dead, Sasuke's dead, their kids are like 40-50 years of age and the only living one from the previous generation is Orochimaru who uses a jutsu to communicate with his former team and discuss whether he should pull the plug on himself or live.
-Hashirama vs Kakuzu - the fight we never got to see.
-Tobirama inventing FTG to counter Uchiha's sharingan (this one's a headcannon)
-The mission that caused Kakashi's dad to commit suicide.
Another fanfiction was The inFamous Spiderman - basically, what if Spiderman was a conduit.
I also tried to make a BvS rewrite called Gods and Knights. Unlike the aforementioned ones, I actually wrote and published the first chapter and was halfway into the second, but I kinda realized that I had no idea what I was doing so I just bailed out.