Crashmo is the sequel to Pushmo. Papa Blox's grandniece, Poppy, comes to visit his new Crashmo park in a "hot air balloon" which is actually kept afloat by birds arranged in a balloon shape. When Mallo introduces himself, he scares the birds away, which prevents Poppy from going home. Mallo volunteers to get the birds back.
The target of each level is located on top of block formations called Crashmos. Mallo must get to the top to reach these goals. Therefore, he must push, pull, and slide the separate blocks to make those on top fall down in a formation that allows him to climb to the top. Blocks are largely independent of the blocks below them, so if the bottom blocks are moved, the top blocks will not move with them unless they are locked in position by the lower block. For example, if the upper block is simply sitting on top of the lower block, it will stay in place and eventually fall. But if the lower block has a formation holding the upper block on the side opposite of the direction it is being moved, the lower block will be pulled along with it.
There is also a Crashmo Studio, where players can make their own Crashmo puzzles, and if they are solvable, make QR codes to share them with friends.