Mini Mayhem, subtitled Floor 1 (Ground Floor or Floor G in the British English version), is the first floor in Mario vs. Donkey Kong: Minis March Again!. Being the first floor, all the levels here are relatively simple and easy, allowing the player to adjust to the game mechanics. The floor most notably introduces Pink Blocks, Yellow Springs and Ladders. The only enemies to appear here are Circus Kongs, one in Room 1-7 and two other in Room 1-SP. The Mini Mayhem Construction Kit is available by default in the Construction Zone, unlike other Construction Kits, which must be unlocked by completing their respective floors.
The backdrop depicts a blue sky and green hills all painted onto a metal wall, with fake clouds hung from strings scrolling across the roof. The soundtrack of this floor is reused from Mushroom Mayhem, the first floor in Mario vs. Donkey Kong 2: March of the Minis.
This floor contains tutorial levels that showcase Pink Blocks, Springs, Ladders and the Key Mini Mario. The player can access and play them by tapping on the "?" icon in the bottom right corner of this floor's level select screen.
In Plus Mode, the floor is subtitled Floor 1+ (Ground Floor+ or Floor G+ in the British English version). Here, the rooms are slightly harder than the normal floor. There is also the addition of Shy Guys and Snifits as enemies, as well as Pipes, Split Pipes, conveyors, conveyor switches, Pop-up Gates and yellow Box Springs as objects. All of these elements, with the exception of Box Springs, are added to the Mini Mayhem Construction Kit once the floor is beaten on Plus Mode.
The backdrop is mostly the same as in Normal Mode, with the only difference being the orange-colored sky. The soundtrack is an original composition.