Room B-6 is the sixth course of the Basement in Mario vs. Donkey Kong: Minis March Again!. It is unlocked by earning 80 silver stars or better from previous levels. The soundtrack of this course is based on the castle theme from Super Mario Bros. and was also used in Mario vs. Donkey Kong 2: March of the Minis as the soundtrack of Lava Dome.
The course features three mini toys.
All minis start on different girder platforms at the top of the level—one in the far left, one in the middle and one in the far right. The Goal Door is located in the bottom middle. There is a Thwomp between every two minis, and the ground at the bottom as well as the platform above the Goal Door are covered in spikes. Using Pink Blocks, the player has to guide the minis to the Goal Door via an opening to the right of it, while protecting them from the Thwomps and spikes in the area, in order to clear the level.
Mini Mario Card
The Mini Mario Card is located next to the Thwomp on the right. The Thwomp initially stands in the way to the card, and the player has to use a mini to coax the Thwomp into attacking and move it away from there. The player must then place some Pink Blocks to both keep the Thwomp away and to form a path to the card, then have a mini toy come from the left to obtain it.