World-e

World-e is a bonus world found only in Super Mario Advance 4: Super Mario Bros. 3, and not in previous versions of the game. The world itself is separate from the main adventure, and is to be played at the player's leisure. Although it sports no standard levels within its vicinity, World-e features a Warp Zone that can warp Mario or Luigi to brand new levels, provided that the player has scanned in and loaded the appropriate level cards with an e-Reader.

Hidden within the new levels are Advance Coins. If the player accumulates enough Advance Coins, they will gain access to the three Toad Houses in the area, where they can play Mini-games in exchange for a few of their grand total of coins from World-e. Unfortunately, due to the limited support for the e-Reader outside of Japan, non-Japanese players will only have access to fewer levels, and will only be able to collect enough Advance Coins to enter the blue Toad House (a digging Mini-game).

Certain levels have an e-Coin hidden inside them. e-Coins are usually well hidden, and can only be collected once. They are then put on display in World-e's castle. However, due to the premature cancellation of the e-Reader outside of Japan, only three e-Coins have can be obtained elsewhere; the Mushroom e-Coin, the Super Leaf e-Coin, and the Starman e-Coin.

Trivia
World-e is an island in the shape of a lowercase "e".