Finally finished. It was ..wonderful. Simply wonderful. My patience and brain worked overtime (earn your happy ending indeed), but finally got the true ending, which was very satisfying (except for the poor Kid). To tell the truth, by the end the game became so great, I'm sorry it ended, and wouldn't mind it going on. The art (mainly the CG Events) are beautiful, as is the music (think Deus Ex, Unreal and Final Fantasy -ish).
As I said in the picture thread, it's a japanese visual novel (choose your own adventure books with voice over and music), with a very complex (comes close to the Legacy of Kain series) and compelling plot, which, while explained in the end, still teases you to figure out just what the hell is going on.
The main plot is this: at the beginning you choose one of two characters: Takeshi, an idiot, or Kid, a young boy with amnesia. These two and several other people get trapped in an underwater theme park, where they are trying to survive until help arrives, while some of them chase after their own agendas. And afterwards dealing with the problems presented by the repercussions of the accident. The characters are complex, and presented as simple humans with virtues and flaws (Takeshi for instance, tells crappy jokes, doesn't think stuff through, but is determined to help everyone who needs it).
I honestly suggest it to anyone who likes good plots and/or great atmosphere.