The most recent endeavor that I found, The Garden Kingdom was five months ago. It was a terrific story that generated quite a bit of interest and interaction at first but wasn't completed.
Prior to that, there had been a few other similar attempts made on Steemit. One, Short Story and Choose Your Own Adventure in the Interview is limited to a single post where the reader scrolls to a numbered section to continue the adventure.
Another, An Interactive Story had readers vote in the comments for how they'd like the story to continue.
Each of these endeavors were of great quality but did not generate much in the way of interaction. The addition of the riddle that @f3nix has incorporated into our Quest In The Realms is our way of keeping the readers excited beyond just the reading of an awesome story.
Your multiple-ending text adventure DApp sounds quite interesting and I hope that it proves to be a great success! If you've any other questions, I'll be happy to be of assistance. Enjoy your evening (or day)!