From the Super Mario Wiki
Twilight Valley is the sixth world of Mario vs. Donkey Kong: Tipping Stars. It is also the last main world visited, taking place before the game's conclusion, when Mario finds out he and his Minis had been lured to a surprise party by Donkey Kong and Pauline.
Pink Blocks are the new gameplay element that is introduced in Twilight Valley. Using the stylus, the player can stockpile these blocks and fill in special slots with them, in order to guide the Minis and enemies appropriately. Other gameplay mechanics, such as Springs, Cannons, Color Switches, Blue Lifts and Red Girders, return from past levels. There are several Thwomps as well, along with a few Fire Piranha Plants and all three types of monkey robots seen in previous worlds.
Twilight Valley is set on a countryside meadow, close to a few Mushroom Kingdom-like hills located in the far background. A Georgian-era mansion is prominent among the hills. The word "twilight" in its name might owe to the pink color of the sky, which is how it often appears at dusk.
Names in other languages