Meka : This program is called an emulator.  But what does an emulator?
First of all it 'reads' the sega master systemgames (the sms extention files) and then plays the game. (or gg extension files for game gear)
Second, it also can play sega game gear games.

Without an emulator you can't play the games (their are more emulators but i think the meka emulator is the best.

The emulator is 350 kb large so start downloading ....
On this emulator you can play sega master system and sega game gear!