The one that you played several times without losing it's allure. You know everything about this game and when you play it you feel like there's only the screen and you. Nothing else matters and nothing else exists while you play it. The one game that makes you feel like you're in love when you're playing.

Mine is Metroid Prime.



Reasons? Well, back when it came out it was a huge new concept, especially for Metroid. Graphics were stunning for the era, one of the best looking games out there and the level of detail? It's borderline stupid on how much detail they put into this game. It has exploration, collection, information, lots of lore, very varied environments, varied enemies... it's a piece of art.

It reminds me of Halo in a way.

Dragon age franchise

DA:Origins, got every achievement there and I mean everything. All endings, all starts, all choices, everything

@Kuro: The first Metroid came out in 1987. Additionally, Metroid Prime and Halo have only one year of difference and although I like the original Halo, it doesn't hold a candle against Metroid Prime in all areas. Furthermore, the new development team for Halo 4 onward (343 studios, I've friends there), is taking a lot of "reference" from Metroid Prime if you know what the quotation marks mean. Lastly you didn't contribute with your selection =p

@BWG: That's nice! I never got to play Dragon Age, though.