999: Nine Hours, Nine Persons, Nine Doors (or 999 for short) is a visual novel/adventure game for the Nintendo DS in late 2009 and 2010. It was published by Aksys and developed by Chunsoft, long before they merged with Spike, which might sound odd, as the other thing you potentially know them for is... Pokemon Mystery Dungeon. Considering what happens in the first 40 seconds of this game, that is some amazing mood whiplash.
When it comes to the actual game, it's a "visual novel" of sorts so it has lots and lots of words. Some of the talking bits can get incredibly long on their own merit, but there's also occasional breaks in that for some proper gameplay. Namely puzzle solving in a giant room, wherein you find things that help you try and leave it. If that sounds remotely familiar, you've probably played a flash game in the past 12 years or so. Unlike many of those "escape the room!" games, though, this one is actually fun to solve the puzzles for and there's plenty of incidental dialogue to find too. Some of it is boring and not worth looking at, but there's some gems in there that's rather easy to miss if you're not looking for them. It gets likened to an adventure game more than anything else for those segments, but I think that's misleading since the puzzles can be solved by rationally thinking human beings. There is also internal consistency, which is nice.
For what is described as a novel, it does have a pretty good degree of replayability in that it has 6 possible endings. Which ones you get are determined by a few clear choices you're presented with throughout the game.
I'll also include videos of things that I think might warrant them for one reason or another. There probably won't be too many, but I'll also include screenshot/gif versions for those that can't/don't want to watch the videos. I'd recommend doing it if you can though, since there's small bits and pieces you can miss if you don't (nothing too major; just some minor sound bites that are kinda clever and all that).
Oh, and there's a sequel for the 3DS and Playstation Vita called
(Disclaimer: no hats were eaten during the making of this LP.)