Taking the role of David Pierce, ace pilot of the SeaBlade Squadron, players tackle 39 air and sea search and rescue missions to support the Southern Alliance in the battle against the Northern Warlords' aggression. Cataclysmic disasters have reshaped the 24th century world, creating chaos and hazardous regions where innocent civilians are trapped under the tyranny of the North. Missions take place in six post-apocalyptic areas: Hokkaido (oil-refining center), Venezuela (volcanic basin), Colorado (now an island with abandoned NORAD bunkers), Texas (turbulent sandy island), London (valuable minerals), and Iceland (excavation site of an alien ship of vast size and power).
Five types of SeaBlades are available, each with unique attributes of speed, shield strength, and passenger capacity. The Gatling Gun, basic weapon of the air/sea rescue vehicle, and all weapons are replaced by missiles (standard, heat seeker, and freeze), lasers, forward bombs, napalm bullets, and an Energy Claw when the vehicle passes over the appropriate icon. Picking up an icon for the currently active weapon powers it up to a maximum of three levels, providing additional firepower. Other power-ups include health, turbo boots, invisibility cloaks, energy shields, and score multipliers.
Options such as left or right thumbstick steering control, three levels of difficulty that affect the strength of enemies, and multiplayer action for up to four pilots allow customization of gameplay in SeaBlade. Three types of multiplayer games include Chaos Reigns (highest kill count), Tag (last player holding explosive weapon when time runs out is eliminated), and Moving Target (first to hunt down computer-controlled vehicle wins).