Sonic CD, developed by Sega, is a platform game for the Sega CD system, originally released in 1993. It's part of the Sonic the Hedgehog series and introduces players to time travel mechanics, where Sonic can navigate to different time zones in levels. The 'Not For Resale' edition was often bundled with Sega CD hardware and wasn't meant to be sold separately. It's known for its vibrant graphics, unique soundtrack, and the debut of characters Amy Rose and Metal Sonic. The game's genre blends fast-paced action with exploration.