Metroid Prime (2002)
One of the best-selling games on the GameCube, and the second-best selling game of 2002 behind Grand Theft Auto: Vice City, there's no question that Metroid Prime is a highly regarded game. What made it special was how it captured the magic of the early 2D games and made you feel like you were really in those worlds. Far more than just a first-person shooter where your view of the world was the tip of a gun bobbing in front of you, Prime made you feel like Samus and did so by creating an atmosphere that was immediate and palpable. Given the technology of the GameCube (and later the Wii, for which it was re-released) it was truly incredible how effectively it conveyed a sense of presence in a large, richly-detailed and open world using techniques that games like Ken Levine's Bioshock were able to build on in subsequent years. 15 years later, it's still a reference point for successful, narrative and exploration-based first person action games.