Several unofficial hacks of Battle City were produced by the Chinese company Yanshan Software in the early 1990s, the most common being Tank A 1990. They featured more levels, new level layouts, new power-ups like a handgun which maxes up the tank's firing power, the ability to cross water, and other modifications. These hacks became popular in China and other countries where Famicom clones were widely distributed, and are frequently found on pirate multicarts.