In this game, Mappy the Mouse has been given an extended family, including his wife, "Mapico the Mouse" and his son, "Junior the Mouse." However, Goro and his Mewkie thugs are back and trying to stop Mappy from making a new life. Mappy must survive through the levels collecting: Cheese for his girlfriend's (Mapico's) Birthday. Then Re-do them again but collecting rings for his wedding with Mapico. Then again collecting Christmas trees for the Christmas party. This time Mappy collects baseballs for his son's (Jr's) birthday. There are 4 worlds and 8 levels in each (A train station, The Wild West, an Island setting, a Jungle, a Pirate-ship, Graveyard, a Small Town, and a Giant Castle). Goro goes through many changes during the levels corresponding to the level Mappy is on.
Source: Wikipedia, "Mappy-Land", available under the CC-BY-SA License.