To back up for a little bit for anyone who hasn't played Pandemic yet (which is probably most of you), it's a co-op board game where the players are working together to stop four simultaneous, virulent, disease epidemics from wiping out mankind. Each player is assigned a "role" with one or two special abilities, and you all work together and coordinate your actions to cure the diseases. The diseases are color-coded, and to cure a disease a player has to discard five cards of the same color as the disease, while in a city with a research center. This is much easier said than done, however, because the game imposes a strict 7-card hand size limit, and the cards are also very useful for other things like building research centers and fast-traveling around the map. Once all four diseases are cured, the players all win. However, the players all LOSE if the deck they draw from runs out, or the stock of markers for any one disease runs out (meaning that all of the markers for that disease are on the board), or if there are eight "outbreaks" (an outbreak occurs whenever a city gets more than 3 disease markers of the same color, at which point it ruptures disease markers into all neighboring cities, which can cascade more outbreaks if they're already full). So, lots of ways to lose, one way to win. Also, even if you've "cured" one of the diseases it can still pop up and spread around until it is completely eradicated from the board, which is no mean task.
This game was originally released at the height of the piggy-pox and bird flu scare, so its theme was very topical a couple years ago, but I think they probably could've given it longer legs if they'd tacked on a "zombie" theme, even though I feel at this point that zombies have pretty much reached market saturation. With the current theme, it feels just a little bit like I'm playing an edu-game, and one whose topicality has passed. I also think (especially with a zombie theme) that this game could do really well on Xbox Live.