9 Hours, 9 Persons, 9 Doors (999 for short) is the first game in the Zero Escape series. It was released on the Nintendo DS in 2010.

The story of this game starts with a young man named Junpei, who wakes up aboard a ship at sea with no memory of how he got there. He finds a strange bracelet attached to his wrist and is unable to unlock the door in front of him. As the room quickly begins filling up with water, the gamer takes control of him and we must help him escape the room, where Junpei eventually meets up with a group of strangers who have been put in the exact same predicament.

There are a series of different rooms to escape from. You have different paths that you can go down which lead to multiple endings, and one true ending. Each room has a number, as do all of the bracelets that the characters wear. You have to split up so that your bracelets add up to the number on any given door. You then collect items around the room and put them to various uses, all the while gaining backstory on the other characters, trying to put the pieces together.

One mystery individual is the mastermind behind the whole "game". You won't know who, or why, until much later on. Additionally, some characters end up going mad, and you can experience some truly gory scenes as things get violent. This is by no means a game for kids (it is rated M). This is, however, a really excellent game, with a really engaging mystery.

If you like puzzle games but you're looking for something a bit more mature, and you don't mind reading, this woild be an excellent choice. Just be forewarned that you probably won't get all of the answers you're looking for without continuing on with the other games in the series.