Sonic the Hedgehog Pocket Adventure
In August 1999, SNK announced that they were collaborating with Sega to develop a "Sonic the Hedgehog" game for their Neo Geo Pocket Color handheld system. The game was developed by SNK, with supervision from Yuji Naka and Sonic Team at Sega. This marked the first time Sega was directly involved in the development of a "Sonic" game for a non-Sega platform. The team planned for "Sonic Pocket Adventure" to be a return to the classic 2D gameplay style found in the "Sonic" games on the Sega Genesis. In particular, many game design and visual elements are borrowed from "Sonic 2". The game's background music tracks are also 8-bit renditions of music from "Sonic 3". "Sonic Pocket Adventure" was released first in North America on December 4, 1999. SNK released a system bundle with the game included for the holiday season. The game was released in Japan two weeks later, and in Europe in February 2000.
Sonic CD
The Sega CD's flagship game, "Sonic CD" was conceived as an enhanced port of "Sonic the Hedgehog 2", but was reworked after lackluster sales of "Sonic 2" in Japan. Sonic co-creator Naoto Ohshima directed and Sega developers designed the game to show off the technical capabilities of the Sega CD. The game features the debuts of Amy Rose and Metal Sonic, and includes animated cutscenes produced by Toei Animation. Two soundtracks were composed for the game: the original score was composed by Naofumi Hataya and Masafumi Ogata, while the North American score was composed by members of Sega Technical Institute.