As I saw you were asking, Homestuck.
It's an interactive web series made through quick sketches in Paint, where the author adapts the story to whatever his readers tell him to do. It's currently on Act 6 Act 6 iirc, but won't be updated any time soon (D:) since the author is working on a game based off of it. If you're up for a novel-sized read, I'd recommend it. It has lots of allusions to other stories on the site from the same author (notably during Act 3). The author states that Homestuck is, as a project/webcomic, still under his control, but, as a story, never was and still isn't. It has a lot more depth and humor than you'd expect; just get to Act 2 and it gets rather deep and entertaining.
From Wikipedia:
"Homestuck is a webcomic written, drawn, and animated by Andrew Hussie and is the fourth overall webcomic published on MS Paint Adventures. The comic uses a combination of static images, animated GIFs, instant message logs, Flash animations and games created in HTML5. It has been noted for its unusual length – over 6000 pages as of 15 March 2013[1] – and complex plot.[2]"