If you're an XBox LIVE gold member, you can download Dead Rising 2 and Dead Rising 2: Case Zero free for a limited time:

"Today until August 31st, Xbox Live Gold Members can grab BOTH Dead Rising 2 (Normally US $29.99) and Dead Rising 2: Case Zero (Normally 400 points) for free. Download them both today.

The “Games With Gold” program gives Xbox LIVE Gold Members 2 free games to keep each month. A new title will be available the 1st and 16th of each month."

Here are more details on Dead Rising 2 and Case Zero:

"Set several years after the events of the first game in the series, Dead Rising 2 contains all the fun and over-the top carnage which gamers associate with a zombie apocalypse. As with all releases in the Dead Rising series, it is a survival horror game. Players take on the role of an all-new character, with equally new motivations to survive and resources to do so. These resources include new weapons, expanded weapon combination/creation possibilities, and even two-player coop functionality. The game also features a 4-player online multiplayer mode, an optional prologue to the game available as downloadable content and a dramatic increase in the number of zombies that can be faced at once.

The sequel to the million-plus selling Dead Rising, Dead Rising 2 sees the player take on the role of former Motocross champion Chuck Greene, who has come to Fortune City, America's newest gambling paradise, to compete in "Terror is Reality," a gruesome game show that dares contestants to survive zombie-filled environments for big money prizes at the delight of TV audiences around the globe. Chuck's motivation for taking part and risking life and limb is his daughter Katey, who since being bitten by a zombie requires a daily dose of Zombrex to prevent her from turning into one of the living dead. There's no denying that Zombrex works, but since it's the only drug on the market, its price is high.

During his time in Fortune City a zombie outbreak occurs and Chuck must survive the onslaught of the undead for 72 hours. Pitted against two fearsome threats - tens of thousands of zombies and the constant countdown of the clock - while potentially rescuing other survivors of the zombie apocalypse, players must also unravel the greater conspiracy behind the outbreak and as importantly find the Zombrex necessary to stop Katey from joining the ever growing zombie horde. Players will shoot, stab, carve and drive their way through enemies in order to beat the clock and survive 72-hours in the darkly comedic, no holds-barred confines of Fortune City.

Gameplay
Dead Rising 2 delivers more of the signature gameplay that the series is known for plus a number of new features. Players who might need some help or simply want to share the zombie bashing fun with a friend will now be able to play in online 2-player co-op. Simply use the in-game transceiver to call for assistance at any time and once your partner has accepted, they will arrive by your side for double the action.

With hundreds of zombies on screen at any one time, the original Dead Rising forced gamers to take everyday objects they found in the mall and use them as weapons. But now, in Dead Rising 2 with thousands of zombies filling every square inch of Fortune City, Chuck is going to need to be even more resourceful and inventive by creating combination weapons to save the day. Players will be able to take two objects, a roll of tape and with a little inventiveness create an advanced zombie-killing combo weapon - a piece of wood and a lawnmower become Portamower, the handheld mower that cuts zombies down to size in an instant; while a garden rake and car battery combine to create an electrified zombie prod. The more combo weapons a player uses, the more Prestige Points (PPs) they will gain along the way in order to level up Chuck.

Optional Downloadable Prologue
Ahead of the full game, Capcom will release original downloadable content Xbox Live with Dead Rising 2: CASE ZERO. This prologue consists of unique content not available in the full retail release of Dead Rising 2 and will introduce new protagonist Chuck Greene as he and his daughter find themselves caught in the desert town of Still Creek that has been overrun with zombies. Set two years after the Willamette incident and three before the action of Dead Rising 2, Dead Rising 2: CASE ZERO will help bridge the gap between the two titles and give players a taste of the new gameplay they will experience in Dead Rising 2 as they create combo weapons, rescue survivors and take on a ruthless psychos before making their escape."

Source: Major Nelson