In this game, you control the movements of the dolphin so that it swims through as many schools of sea horses as possible, thus accumulating points, while evading the giant squid in hot pursuit. Every once in awhile during the chase a sea gull files from the side of the screen just above the waters. If the dolphin is able to jump from the water and touch the gull, the table is turned and the dolphin is then able to give chase to the squid, dispatching the nemesis as soon as it's caught.
Dolphin innovates in the sound department as well. The dolphin not only moves in the water like a dolphin normally moves in water, the dolphin communicates with the player through sound. As it swims through the water, the dolphin approaches a school of seahorses, blocking the way. Before the wall of seahorses is even visible, the dolphin emits a sound of particular frequency. The higher the frequency, the higher up the opening in the soon-to-appear wall of seahorses. Low-pitched tones indicate openings in the lower sections of the seahorse school. Learning to listen to what's happening while watching the action is not difficult for long. The patterns soon become recognizable enough to at least give time for preparation. Eventually, through enough play, the varying pitches become precise indicators of where the dolphin will be able to go and where the figure should be placed in order to keep it from colliding with seahorse blockades. The seagull also emits an auditory signal as well. Every time the gull appears on the screen, it makes a softened screeching call. The call is repeated as the gull flies quickly from one edge of the screen to another, always just above the surface of the water. If the dolphin has been alert to the sound, it can make a quick trip to the top of the water and leadp up and touch the seagull, then plunge back into the water for an attack on the giant squid.
During the chase - you in pursuit of points and the squid in pursuit of you - waves moving either left to right or right to left are indicated by large white arrows. These waves appear at random in differing areas of the water portion of the screen. The ones pointing to the direction in which the dolphin is always traveling are the most advantageous. They give speed and momentum to the dolphin as it eludes the squid. All the dolphin has to do is touch the wave. Waves going in a direction opposite that of the dolphin's direction are bad news. They hinder the progress of the dolphin, making squidfood of the poor thing. Therefore, if you notice that the wave is not going in the same direction, you should turn around and make your dolphin go the same way as well.
This is a thoroughly satisfying game, unique in many ways in superlative in others. There are eight game variations, four for one-player action and four for two-player gaming. All are interesting, challenging and good fun. The only thing lacking from Dolphin are exploding bombs or streaking missiles. No big loss... for those, you can pick up most any other cartridge and find those featured in those games. Yet another original and inspired effort by the top-tier 2600 software house.