Microsoft's original Motocross Madness was an absolutely breakthrough experience for most of us, simulating for the first time the full exhilaration of free-form dirt bike racing. Since its highly successful release in 1998, no serious competitor has emerged to take up the challenge, so you might have expected Microsoft to stand pat and rest on its laurels. But nothing could be farther from the truth, concretely evidenced by the release of Motocross Madness 2. Developed again by Rainbow Studios, the Arizona-based digital production company that has created content for film and television, has yet to release a dud of a game; this sequel attempts to take the daredevil racing, physics-defying stunts, and bone-crushing crashes of the original to a whole new level. But how could the developers improve on such a critically-acclaimed initial release?

Perhaps the most noticeable difference between Motocross Madness 2 and its predecessor is the introduction of two new racing modes: Pro Circuit and Enduro Racing. Pro Circuit is a single-player career mode where you begin as an unheralded rookie, and then compete in circuits of increasing difficulty to earn prize money and sponsorship dollars to enter future races, pay for bike repairs, and manage medical bills. Your ultimate goal in going through this grueling process is to enhance your reputation and collect new bikes and racing gear in the hopes of making it into the ultimate motocross test, the professional Supercross circuit. The Pro Circuit mode is probably the best addition to Motocross Madness 2, as it adds a lot of strategic complexity to the game and -- unlike some other racing titles' botched attempts to inject resource management -- seems to blend right in with the overall spirit of the product. The other new mode, Enduro, offers outdoor point-to-point racing events set in fully interactive, densely packed environments as diverse as an Arizona trailer park, a South American jungle, an open pit mine, and a ski resort. Containing busy highways, airports, train tracks, and construction zones, this mode requires the most skillful dodging and weaving to succeed. Still, Enduro is not nearly as innovative as Pro Circuit because of its similarity to some of the other open racing modes already included.

Motocross Madness 2 additionally retains the four single-player racing modes from its predecessor: Baja, Nationals, Stunt Quarry, and Supercross, even introducing improvements through redesigned Nationals and Supercross tracks co-developed by Supercross professional, Stephane Roncada. Baja has you racing in remote outdoor environments through various waypoint gates and is less difficult than Enduro because of the fewer obstacles to surmount; Nationals has tight technical outdoor tracks that twist around and have huge elevation changes; Stunt Quarry has you doing amazing stunts in scalable open pits; and Supercross has you run through a series of stadium tracks with the crowd responding to your every move. When considering the two new types of racing together with the four old ones, it is nice to note that all work well together, are of equal quality, and are well integrated into the whole package -- in sharp contrast to many racing offerings that fail in their attempt to encompass multiple types of racing.

As for multiplayer action, you may now form leagues, ladders, and teams for exciting human-to-human competition. Up to eight riders can compete, and this sequel retains the fun Moto-Tag where you try to hold onto a beach ball as long as possible until another player tags you, with everyone else in a desperate frenzy attempting to smash into you. A new online scoring system allows players to post individual Pro Circuit high scores and to gain online win points for multiplayer rankings. The best players who rank among the top 100 online merit a personalized number plate indicating their ranking in every online race. As expected, given who has published this game, the MSN Gaming Zone is available for Internet play.

For added realism in this new version, there are 12 models of licensed motorcycles from Honda, KTM, and Yamaha as well as licensed gear from Fox Gear and Answer clothing. The developers have also added support for engine sizes ranging from 125cc to 650cc, so each machine has unique power and handling characteristics that require time to master. Being savvy about selecting your bike is critical to winning, as each generally does best in one particular type of event. You may also tune the suspension, gear ratios, and brakes on the bikes in the garage. Such bike selection and tuning help you to be able not only to move faster but also to accomplish the 16 colorfully named stunts, including Heel Clicker, Air Walk, Cliff Hanger, Heart Attack, Lazy Boy, and my favorite, Nic-Nac. While to your average buyer having real motorcycle brands to do the riding and jumping might be no big deal, to motorcycle aficionados having the authentic vehicles -- reproduced here with great accuracy in both appearance and performance -- makes all the difference in the world.