Hello!
About "Sonic 2 Demo (not playable, just running demo)" for Game Gear:

This prototype is the Early Game Design that the "Sonic Retro" show images of Sky High Zone and Green Hills Zone?

http://info.sonicretro.org/images/4/4b/S2Title.jpg
http://info.sonicretro.org/images/c/cf/S2_GHZ2.JPG
http://info.sonicretro.org/images/b/b4/S2_GHZ4.jpg
http://info.sonicretro.org/images/4/46/S2_GHZ5.jpg
http://info.sonicretro.org/images/8/8e/S2_SHZ.jpg
http://info.sonicretro.org/images/2/2d/S2_SHZ2.jpg
http://info.sonicretro.org/images/b/ba/S2_GHZ.jpg
http://info.sonicretro.org/images/2/28/S2_GHZ3.JPG
http://info.sonicretro.org/images/3/33/S2_GGmap1.jpg
http://info.sonicretro.org/images/0/03/S2_GGmap2.jpg