From 1991-1994 SEGA (Japan) and Tiger Electronics Inc. (USA) decided to make a special portable system featuring a Sonic game that you can only play. Tiger made 3 models for each game with the game extracted from the Mega Drive/Genesis versions of the game on a portable screen.
The staff at Sonic Stadium (a Sonic website) was talking about those and they said that they found that at Los Angeles, USA.
A comment made by Lukel on the same website said that he/she did have the game in the shed somewhere.
Another version but in the Modern Sonic period was the ones that you could get at McDonalds.