Here are some cheats and tips for the game Space Harrier.
Easy mode:
Hold 2 and power on the Game Gear.
Expert mode:
Hold 1 and power on the Game Gear.
Bonus lives:
Hold the D-pad in any direction + Start and power on the Game Gear.
Level Password
2 EAGF
3 CHFA
5 DGBC
6 HBGA
7 FBHE
9 BFCH
10 HGDA
11 AGEC