Ecco the Dolphin (Pack-In) for the Sega CD is an action-adventure game featuring a unique underwater protagonist, a bottlenose dolphin named Ecco. Players navigate Ecco through a variety of marine environments solving puzzles, communicating with other sea creatures, and using sonar abilities to combat aquatic threats. Enhanced for the Sega CD, this version offers improved graphics, a remastered soundtrack, and additional levels not found on the cartridge-based counterparts, delivering an immersive and serene undersea experience.