Ocean Quest is a game in the match-3 genre. As its name implies, it is set under the sea. The story of the game goes that machines that had been designed to clean the bottom of the ocean have gone mad, and instead of doing what they were designed to do, they have started to poison the sea. It is then up to the player to stop the machines and save marine life from further destruction. Players are given control of a submarine that is able to fire colored balls to lines of balls that roll along reels toward a sea gate. Players must stop the balls from reaching the sea gate in order to stop the poison.
This is done by matching the ball fired from the submarine with those rolling along the reels. Players must fire a ball into a group of two or more balls of the same color. When this is accomplished, the whole color group will disappear from the chain of balls. Its place will be occupied by the other balls rolling behind. Firing is done by aiming at the chain and clicking the left mouse button. Players can swap the color of the ball their submarine is about to fire by clicking the right mouse button.
Ocean Quest provides players with bonuses to help them in their goal. These bonuses need to be caught before they disappear from the screen in order for them to be activated. The bonuses can make a whirlpool, generate a bomb, make the balls step back, or stop the chain temporarily. Once all of the balls have been eliminated, players can advance to the next level.