Dominion

To explain what the game, Dominion, is: A game that includes building the best possible deck of cards to acquire the most number of "Victory" points at the end. Unlike Magic or Pokemon where you start with a pre-made deck of cards, the process of building your deck is part of the playing game. While there is some strategy in playing which cards you have in your hand, the majority of the game's strategy is in building your deck with the winning combination of cards.
The game is really simple and easy to learn. Games can be quick (most last less than 30 mins) but depends on the speed of each person's turn. Turns usually go quickly as the cards aren't complicated. Some turns may last a bit longer if you play a series of "Action" cards like this winning turn by yours truly:

It's rare to find a game that is fun to play with two players but Dominion has achieved that; it can be played with up to four players. The variety of cards can be expanded by purchasing any of the nine expansion sets.
Dominion is definitely a game that will be on the top of the pile of any game collection; it's already becoming one of my all-time favorites.