Hydro Thunder is an extreme arcade racing game... with boats! Well, I think they're boats. They're lke robot boats from the future. Unlike Wave Race 64, this game has a faster sense of speed. A lot of effort and thought was put into the physics engine, so that the boats controlled somewhat realistically. But don't think it's a simulation experience. Real boats don't pick up boosts and power-ups, or launch into the air. The controls are simple, one button to go, one button to boost (when held). Ramps help you go farther, even access hidden parts of the track.
The 14 tracks are imaginative in offbeat environments. There's more than just standard "Tropical Island" track here. There's some kind of apocalyptic flooded New York, the canals of Venice, and a Pyramid with Sea Monsters. Tracks also feature hidden shortcuts to give you the edge over your opponents. Other than ramps, other obstacles include killer whales, and big boats that somehow are faster and more maneuvarable than you. Seriously, there's like like mini cruisers jumping off ramps to avoid your speedboat.
Multiplayer is an annoying situation. The game only supports 1-2 players in all versions, EXCEPT the Nintendo 64 version. In the N64 version, which is considerably slower, requires an expansion pak to be able to play more than that. That means if you've got 3 or 4 players, make sure someone bought that expansion pak.