Sonic the Hedgehog 2 for Game Gear was released on November 21, 1992 in Japan. It was then re-released as a Meisaku Collection edition [Model G-3338] on December 10, 1993.
TIPS AND TRICKS
Level select: During the intro, hold Down+Left+1+2+START. Wait for Tails to blink twice - you should hear ring sounds. Release the buttons and press START.
Infinite extra lives: On Green Hills Zone act 1, when you go up on the first loop, there's a life monitor there. If you're fast enough because of the impulse that you took to climb on the loop, you will take the life monitor and pass directly. Press jump exactly on the diagonal green spring and try to return to where the extra life is, and it will be there again. You can repeat this as many times as you want.