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 the Hedgehog 2
"Sonic the Hedgehog 2" sold over six million copies, making it the second-bestselling Genesis game behind the original "Sonic the Hedgehog". It received highly positive reviews from critics, who commended the game's level design and visuals, although its multiplayer mode was criticized. It has been rereleased on various platforms; a remastered version developed using the Retro Engine released on iOS and Android in December 2013. Two direct sequels, "Sonic the Hedgehog 3" and "Sonic & Knuckles", were released in 1994.