Baseball-e is a direct emulation of the NES game released back in 1986, Baseball Advance, converted for play on the Game Boy Advance through the use of the e-Reader and its Dot Code technology. The game can only be played by swiping Baseball-e’s five cards into the e-Reader device.
The e-Reader has an LED scanner that reads “e-Reader cards,” paper cards with specially encoded data printed on them. Depending on the card and associated game, the e-cards are typically used in a key-like function to unlock secret items, levels, or play mini-games when swiped through the reader. The cards themselves contain data, as opposed to unlocking data already on the device itself.