Each game has several Pushmo. The first bunch are random shapes but later ones are designed to look like something. The goal is to get to the top of each Pushmo. Throughout the story of each game, Pushmo have either children or birds to rescue, but eventually get replaced with flags. The extra levels have flags to get regardless of progress through the game.
Each game also has a level editor that distributes levels via QR codes. To ensure each level is possible, the creator has to complete a level before creating a QR code.
References in other FranchisesSuper Smash Bros. for Nintendo 3DS/Wii U, Mallo has a trophy. In Super Smash Bros. Ultimate, Mallo appears as a Spirit. The game includes music from the Pushmo series. Mallo has his own Spirit Battle in the game as well.
Mallo is available for use (after unlocking) in Super Mario Maker.