Mega Board Mayhem
From the Super Mario Wiki
Mega Board Mayhem is a board from the extra room hosted by Thwomp in Mario Party 4. Thwomp gives no reason he built it, except that it took him six months to make it, and that he is proud of the results. Here, Thwomps are in charge of the shops and many Thwomps, Whomps, and a Ztar hop and dance around below the board.
Unlike normal boards on Party Mode, there are no Stars and Star Spaces found on the board, no special events, and no minigames each round. The goal is simply to get as many coins as possible and everyone starts with 100. To do that, there are many item spaces and Item Shops around, where the players can get Mega Mushrooms, Super Mega Mushrooms, or other items to steal coins from other players.