Ecco the Dolphin (referred to on the title screen as simply "Ecco") is an action-adventure video game released in 1992 for the Sega Mega Drive. The central character, Ecco, is a bottlenose dolphin controlled by the player through a progression of side-scrolling aquatic levels. The game was designed by Ed Annunziata and developed by Novotrade International, and spawned a series of sequels. Ecco is known for its high difficulty level. According to Nintendo Official Magazine, the Ecco the Dolphin series is the only Sega game series to have sold more copies than the famed Sonic the Hedgehog series. It has recently been released for Nintendo's Virtual Console, Microsoft's Xbox Live Arcade, Steam, and iOS.
Source: Wikipedia, "Ecco the Dolphin," available under the CC-BY-SA License.