eCard Reader for the GBA?

[Rob2600]

it'd still be possible to split the game in parts. Since Metroid is segmented by area (Brinstar depths and the like), it could have different sets of cards for that. Not practical, but still possible.

Read this again:

the maximum spec for nes games on the e-Reader, was Mapper 0 (ines spec), with a max of 16K PRG rom, followed by 8K CHR rom. This meant you could not do games like zelda or metroid.