Roar!, a highly-twisted, heavily-intertwined wooden twister coaster from Great Coasters International, opened on May 2nd, 1998 at Six Flags America in Largo, Maryland. Boasting ten main curves and some twenty-one cross-unders and cross-overs, Roar became a hit among coaster enthusiasts and one of the east coast of North America's wildest wood-tracked coasters. Later that year, on the other side of the USA, Vallejo, California's Marine World began finalizing plans for its transformation to a Six Flags park. A relatively recent newcomer to the major theme park scene, Marine World wanted to add some wood to their ever-growing assortment of coasters. So Great Coasters were soon asked to construct a second Roar coaster and the ride opened with the Six Flags convertion on the 14th of May, 1999 and became the cynosure of Six Flags Marine World. Improving upon the east coast sister ride's layout, Great Coasters lengthened the ride's track circuit from 3,200 feet to 3,467, throwing in an additional hop at the end of the ride and reworking the course's pre-station and post-station areas. The main and perhaps most notable difference to set the east and west coast rides apart, however, is the ride's train design. While the original Roar coaster flies along the rails with Philadelphia Toboggan Co. wooden coaster coaches, the west coast counterpart became the first coaster to use Great Coasters' own 'Millennium Flyer' vehicles: open-fronted, 12-rowed trains based on a wooden coaster train design of the 1920s.

Once Roar's Millennium Flyer train is loaded and lapbars secure, the wooden rails start moving past as a beginning element composed of a U-turn and three 90-degree curves leads riders to the lift hill. The chain lift carries the train slowly up to the top of the 90 feet of lift, up and over a twisting, turning layout laid out down below. Once the click-clanking ceases, the train heads straight towards the impossibly-tight curvature of a steep, twisting first drop - and Roar wastes no time in navigating the curving drop to the bottom. The track next wraps around the layout's Fan Curve - a 270-degree inclined spiral that sends the train into a first Camelback Hump. After coasting over the Camelback, Roar dives back down and takes passengers up and around a second Fan Curve over the pre-lifthill curve. Diving down and curving to the left, the coaster speeds over a quick hill and sweeps through a 270-degree banked turn leading into the ride's tunneled section where the train encounters the layout's steepest banked turn. Exiting the tunnel, the track re-traces the exterior of the second Fan Curve and begins the final furious run to the brakes with a high-speed curving hop banked 180-degree turnaround and final hop.