The player controls a submersible fighter shaped as a freshwater angelfish that must fight through waves of mutated marine life.

Deep Blue is a basic horizontal scrolling shooter: players collect power-ups and different weapons to fight numerous enemies.

The game features a single life; the Angel Fish can take a lot of hits before it is destroyed, and even regenerates over time.

The aliens use their infected marine life to attack the shores of the Earth's continents, initiating an invasion from the deep.

Deep Blue was met with lukewarm reception from critics and reviewers alike since its release.