I just beat this gem with all of the endings, and man, what a game! 999 is a visual novel for the Nintendo DS. It's been selling surprisingly well (due to word of mouth). I definitely wouldn't mind seeing more VN type games.
The premise of 999 is that there are 9 people on a boat, and they must go through 9 doors within 9 hours in order to escape (once 9 hours are up, the ship blows up). The story is more complex than that and does flesh out the characters quite a bit, but that is the gist of the story. I don't want to spoil anything as it's good to go into the game fresh (and avoid message boards relating to this game as people have a tendency to spoil the games story/ending). You have the story (which takes up most of the game), and some puzzles scattered throughout. During the course of the story sections, you have choices that you must choose (like those old "choose-your-own" adventure books, where it'll tell you to go to a certain page when selecting a choice)
Cons: The text scroll speed is pretty slow, but you get into the game so much that it's not too noticable. Once you beat the game once, you can replay it for the other endings and you have the option to skip the sections that you've already read through.
Overall, I highly recommend it. It's a definite change of pace in today's gaming (where FPS, sports, and action games seem to dominate).