Blue Mushroom House
From the Super Mario Wiki, the Mario encyclopedia
The Blue Mushroom House contains one of the special mini-games found in World-e in Super Mario Advance 4: Super Mario Bros. 3. It is a blue-colored Toad House unlocked after collecting 30 Advance Coins. The player must pay 30 coins each time they play this game. Until the release of the Virtual Console version of the game, the Blue Mushroom House was also the only Mushroom House that could be made accessible by the player, largely due to the premature cancellation of the e-Reader line outside Japan.
Mario or Luigi starts the mini-game in a cave, and two sections of digging earth (first seen in Super Mario Bros. 2). Mario must choose one of them and dig until fall to another level. There are more sections to choose (two for each previous section). Digging once more, Mario will fall to a small area divided into four areas. One of them contains a Treasure Chest, while the others are empty. If the player digs to the chest, they will get a random item, but loses if they reach an empty dead end.