Ok, next stop isn't Quake4...instead I'll give you the scoop on Indigo Prophecy.
This game is a sleeper hit. The closest I've seen to a 'cinematic' experience. It's like playing a game of Clue, or reading a choose-your-own-mystery book, but wrapped in the context of a game. In order to progress, the game asks you to perform simple tasks, and choose the direction of the story.
As the story marches forward, you get to play the part of a few main characters. It's sort of a 'who done it', thriller, occult theme....where you play both sides of the story, trying to unfold the mystery.
My favorite part of the game is the pacing. This isn't like an RPG, where you have to talk to 50 different characters, each one having a dialogue tree 20 pages long. In this game, you do interact with people, but they put you on a timer. You might have 4 ways in which the conversation can go, but you have to pick one before the timer runs out. If you don't pick, the game chooses a default path. Once you've picked a conversation branch, you generally can't go back. This keeps things moving forward, and forces you to think fast.
The game mechanics are fairly intuitive, satisfying, and do a good job of connecting you to the actions that your characters are going through. Sometimes, you are running around looking for clues to the mystery, sometimes you are performing a sort of mini-game that involves your character doing all sorts of stuff (dodging things, boxing, climbing..etc). How well you perfom can either have major or minor reprocussions. If you fail to dodge a flying refrigerator, the game will end. If you fail a game involving your 'intuition', you won't get as many clues as you might have otherwise - making the next sequence a bit more challenging.
I would suggest picking the game up on Playstation 2, if you have a choice. For some reason, it seems to feel best with the playstation controller.
This is one of those games that manages to create a fresh and unique game experience - one that does an interesting job of fusing movies, and games.
Try it!!