Forbidden Four

The "Forbidden Four" are four NES Games that are unobtainable in, , , and without the use of an Action Replay, e-Reader Card, or Advance Play. The four games consist of Mario Bros., Super Mario Bros., Ice Climbers, and The Legend of Zelda.

Trivia

 * In North America, two Nintendo Entertainment System games were released exclusively through the use of e-reader card; these games being Mario Bros. and Ice Climber. Europe never received e-reader support, so these games cannot be obtained without an Action Replay. Japan never released these cards, but these games was available in Dōbutsu no Mori + and Dōbutsu no Mori e+. For a short time, Nintendo of Japan offered to transfer equivalent save data from Nintendo 64 to GameCube, so it can be played legitimately, however, this service has since been discontinued.
 * The only games that cannot be obtained at all through normal means are Super Mario Bros. and The Legend of Zelda. Interestingly, Super Mario Bros. can be played via Advance Play, and Dōbutsu no Mori + includes a port of the Famicom Disk System version of The Legend of Zelda. This is odd as the English release replaces that with the English Nintendo Entertainment System version of it, even though the game is completely inaccessible. This has led some to believe that these two games either are obtainable through an undiscovered universal code or were originally intended to be unlocked via e-Reader as well, but e-Reader support has died off before it could happen.
 * Advance Play is when the player links his or her Game Boy Advance to his or her GameCube to download the Nintendo Entertainment System game to the handheld temporarily. This is not available for games that were originally produced for the Famicom Disk System, such as Clu Clu Land D and The Legend of Zelda. It is also not available for games larger than 192 kibibytes, such as Punch-Out!! and Wario's Woods, which cannot fit into the Game Boy Advance's RAM. All other games can be played on Advance Play, but their graphics are stretched by about 17% on the screen's display and are limited to one player.