When a US fleet is trapped by an alien attack, its crew must fight to survive in 26 intense campaign missions. With varying objectives, such as eradicating all enemies or retreating, the player's goal is clear: protect their ships and eliminate the threats.
The gameplay revolves around strategic ship movement and combat. The player must consider factors like ship range, size for navigation, point of attack, water depth, and unit health to gain an advantage over the enemy. Each commander offers a unique passive boost that can be upgraded using special bars filled by defeating enemies – but the alien commander has a counter to this.
While standard ships differ mainly in size and range, there are also special units like supply vessels for missile and fuel replenishment, repair vessels for keeping units alive, and rubber rafts for capturing ports. In ship-to-ship combat, players can engage in duel mode, targeting each other directly with missiles. Skirmish mode allows the player to replay completed campaign missions with their preferred commander.