Forget everything you know about downloadable content ("DLC") for your video games, such as extra songs, a bonus level, or a new multiplayer map. Rockstar Games' GRAND THEFT AUTO IV: THE LOST AND DAMNED (1600 Microsoft Points, or $19.99), the first of two planned episodes for Xbox 360 owners of Grand Theft Auto IV, redefines what's possible in DLC with the beefiest game expansion to date. But as with the main game, The Lost and Damned is laden with mature content and should be kept away -- far away -- from children.

Before we get to The Lost and Damned, a quick primer on the "GTA" games for the uninitiated: Gamers play as a member of the criminal underworld and can go virtually anywhere and do anything in a fully realized 3-D city with pedestrians, traffic, and storefronts. Played from a third-person perspective, this includes carjacking any vehicle, accepting run-and-gun missions (or racing-based objectives), interacting with seedy characters, and making money to fuel future endeavors. Last year's Grand Theft Auto IV, told the story of Niko Bellic, an Eastern European immigrant trying to make it on the streets in a fictitious metropolis known as Liberty City. Grand Theft Auto IV: The Lost and Damned is a 1.78GB download -- via the Xbox Live online service -- that adds a ton of new content to the original game (GTA IV disc required) including a new storyline, characters, missions, vehicles, weapons, music, multiplayer modes, and other content (such as watchable TV shows inside the game). At the start of this expansion game we're introduced to our new protagonist, Johnny Klebitz, the "vice president" of a tough biker gang who not only must contend with foes in Liberty City (namely, other gangs and the cops) but also must cope with power struggles inside the gang, too -- as we learn from the opening cinematic sequence. The standalone story fits nicely alongside the original plot, and you'll intersect with Nico (both directly and indirectly) throughout this 10-hour adventure.

Rather than tackle missions by yourself, this expansion is all about "gang banging" with your crew, such as riding (or racing) the streets in a pack and partaking in many gang wars together. The hogs handle nicely, so there shouldn't be a learning curve when it comes to the controls. As with past "GTA" games, The Lost and Damned can get quite violent, even from the first scene when someone's face is pressed against a spinning motorcycle wheel at a bike shop.

Along with the new single-player missions, the downloadable game offers many new multiplayer modes including the ability to smack opponents off their bikes while in a race to the finish line and a co-op mode where you can either protect a bus filled with informants or ride a hog as part of The Lost gang determined to destroy it and the snitches inside. Needless-to-say, the content is designed for a mature gamer and for someone who enjoys the virtual, visceral thrill offered by past "GTA" bad boy games. With this in mind, it truly is a fun ride worth considering.