At the start of a level, crates begin falling from the sky. Each one has a picture of the block it contains on it. Stack these blocks and build a tower up to the hot-air-balloon to finish the level. However, it is not that simple; the water at the bottom of the level rises, and if there are any holes remaining in the tower, it gets destroyed. Also, several enemies randomly appear, some stealing your crates, and some dragging you into the water. There are also items in bubbles that give you a power-up or help to destroy an opponents towers.
Source: Wikipedia, "Egg Mania: Eggstreme Madness", available under the CC-BY-SA License.