(Apparently there is a 4th, but I haven't played it.)
I've played the 4th now and I really don't recommend it. Not that it is terrible, With the first three there were different outcomes (surviving outcomes rather.) Granted, the 4th installment focuses on a specific branch from the 3rd game, but I wasn't too enthused with it. I highly recommend 1 through 3 though.
It is a choose your own adventure book style game that is set in a post-zombie-apocalyptic setting and it's done really well. Anyway, it inspired me so I whipped yesterday up a little engine that will run similar games, the Cyoa Engine (Key-oh-uh.) So far it is a really simple engine; basically just a background with music and some UI controls on top, but I'm going to add a track system so that you can jump back a little and possibly some animations.
The editor is almost finished:
And here's a shot in-game (this was put together manually; the editor doesn't support anything beyond a scene with a background at the moment):
I'm still working on Treasure House, trying to finish up the items, characters, and objects and figure out the last two puzzles. I'm hoping to start working on the art for the scenes and objects within the next couple days.
For those interested, the cave image was found on wpclipart.com (http://www.wpclipart.com/geography/features/cave_entrance.png.html) via a Google Images search.