Insert the Metroid: Zero Mission cartridge so that the screw socket is exposed, but the screw itself should not be exposed. Turn on the GBA. At the M: ZM title screen, press Start. Afterwards, go to Options, then Original Metroid. Right when the Metroid title screen appears, yank out the M: ZM cart! You should be able to play the original Metroid without the M: ZM cart! If it doesn't work, try again! I've tried doing some weird "crooked cartridge" tricks do see if I can mess with the game and I came across this discovery. I retried this process in order to find a uniform method of doing this trick. Please reply if this trick works!
Thread title: