I just finished reading the Problem Sleuth story in its archives, and that quickly turned from a parody of text adventures and point-and-click adventures into something much, much more...
Now I'm starting the Homestuck story (which I've learned is nearing a conclusion of sorts.) I'm only in the second chapter of it, but it's definitely built on all the stylistic touches that developed with Problem Sleuth.
I also, uh, read... Bard Quest and Jail Break. They... well, they weren't as good, but the author is aware of that and only puts them up so that you can see the evolution of the website and story style anyway.
So... yeah. If you've got a bunch of hours of free time, I *highly* recommend Problem Sleuth. And if Problem Sleuth isn't your cup of tea (though I suggest giving it until chapter 2 at least), then definitely try Homestuck.
It's worth mentioning that the website as a whole is definitely NSFW, and even if you avoid the worst parts you're probably going to be mostly a low R/strong PG-13 rating (but mostly R.) Ignoring that, though, it's great.
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