A series of puzzle games.
The objective of the game is to guide special shaped meteors though a series of rotating disks and save the planet Roo and ultimately the Roogoo race. Shapes include triangles, squares, circles, stars, and so forth. Each level, the player is given a set level of meteors to try to allow safely to pass to the bottom.
When properly aligned, the disks allow the blocks to fit into the hole. When the meteor pile is heavy enough, it descends to the lower disks. When a stack hits the wrong shaped slot, the player loses meteor blocks until all of the blocks are gone or the player manages to save some of them by properly aligning them before they are all gone. The object is to get as many meteors into the bottom rung as possible.
Obstacles include "Meemoos", enemies who impede the blocks' movement. To get rid of the enemies, the player must quick drop a la Tetris the blocks to knock them out of the way; doing so causes the meteor block to bounce in the air, so it is possible to eliminate Meemoos on other slots, so long as the final location for the stack is the current slot. Butterflies will sometimes grab a falling stack and lift it to an upper rung, and the player must rotate the disc so that it goes through the proper slot.
Source: Wikipedia, "Roogoo", available under the CC-BY-SA License.