The silent war that rages beneath the waves intensifies and takes a radical and...strange...turn.
The engineers at Archer Inc., the most powerful weapons conglomerate in the world, have discovered new, innovative materials and herefore unknown energy sources in the deepest and most secret of oceans. Thanks to tremendous research and development progress in recent months, the submarines now carry unstable weapon prototypes.
On the fringe of this abyssal war, exploration vessels take advatage of these emerging technologies to dive ever deeper and find new navigational routes.
In Captain Sonar, up to eight players take on roles manning a submarine in a fierce battle against rival players. Captain Sonar: Upgrade One adds new elements to the base game, including five new scenarios, two new weapons, eight erasable markers, and different ways to play the Captain and Radio Operator roles.