Dominion is a card game for 2-4 players (or up to 6 when you add the expansion), combining elements of "German-style" board games and trading card games (ie, Magic: the Gathering), except it provides all you need to play in one box.
Each player starts with a deck of 10 cards, seven Copper cards and 3 Estates. There's a pool of 25-50 additional cards available, from which about 10 are selected for each game. The goal of the game is to have the most points when the game ends (by running out of certain piles of cards).
You play in rounds, with a 5-card hand, drawn from each player's own deck of cards. You use Copper to buy new cards, which are added to your deck. The trick is that the cards that earn you points aren't worth much during play. That is, while you can spend Coppers to buy new cards, cards like the Estates are dead weight when drawn into your hand. The other 10 cards available for purchase may allow you do things like draw more cards, or get discounts on your purchases.
So, you have this growing pile of cards, which you shuffle through and draw into a hand, which you can then "spend" to buy more cards, which you will (eventually) shuffle and continue playing. The challenge, then, is to manage the balance of cards in your deck, building it as you play the game. If you buy too many point cards, too early, you'll run out of "gas", and watch your hand "clog" with cards you can't play. On the other hand, if you don't buy point cards quickly enough, you'll be behind the competition when time runs out.
And, because each game generates a different set of cards from the game's pool (originally 25 cards, now up to 50 with the expansion), your strategy has to adapt a little each game. If the "Village" was the run-away star of your last game, but now it's not available, you have to change the way you approach the game.
And you have to watch your opponent's purchases, as well. They might buy a "Witch", which puts "Curse" cards into your deck (-1 point and dead weight when drawn). Now you might want to look for solutions: there might be a card that neutralizes the Witch, or which turns the Curse into an advantage for you.
The Spiel des Jahres (SdJ) is the gaming world's Oscars. It's given out a few weeks in advance of the Spiel game fair, held even year in Essen. (I bought Dominion after playing it at it's Essen debut a year ago.) The SdJ award often goes to games that are family-friendly, and Dominion is, in some respects, a more complex game than is usually recognized by the SdJ. Still, with only a few exceptions, the SdJ usually signifies a game that is about to "break out" onto the gaming scene, if it hasn't already.
On the other hand, Dominion was recently announced as a nominee for this year's Diana Jones Award. First: there is no Diana Jones. The award is fashioned from the remaining bits of the "Indiana Jones Role-Playing Games" — reputedly one of the worst games in the history of games, each and every copy destroyed by request of the publisher — and "Diana Jones" is all that can be read of the original title, a sort of "traveling trophy".
The secretive cabal responsible for the Diana Jones Award is comprised of game designers, and their emphasis is on games that, in some way, effect the field of games. This has led to some odd nominees, as they occasionally select a "style" or "community" of games. In 2006, for example, the winning nominee was Irish Game Convention Charity Auctions. This year's nominees include Jeepform, a style of live role-playing games popularized in Scandinavia.
Dominion isn't a lock to win; this year's Diana Jones nominees are all reputedly good games. Still, I can't help hoping. The only other time that a game has won both the Spiel des Jahres and Diana Jones awards was in 2005, when Ticket to Ride won both.