Monster Party is a video game for the NES, released in North America in 1989 by Bandai. It was and remains a relatively obscure platform game for the console, having a small following among some players. The game both pays homage to and parodies horror pop culture, alternately featuring enemies and locations based on classic horror icons, and parodic reinterpretations.
In the 2000s the game became infamous in online gaming circles when prototype screenshots of a Japanese Famicom version known as Parody World: Monster Party (パロディワールドモンスターパーティー, Parodi Wārudo Monsutā Pātī) began circulating showing different bosses and parodies. No version of the game was ever released in Japan. On May 26, 2011, a prototype of the canceled Japanese release was listed on Yahoo! Japan auctions, closing at a very high price of ¥483000 (approximately $6000 in American dollars). On July 3, 2014, the unreleased Japanese Famicom version was leaked online.