Thundercade, also known as Twin Formation and 特殊部隊UAG (Tokushu Butai U.A.G., "Special Forces U.A.G. (Un-Attached Grenadier))", is a vertically scrolling shooter developed by SETA and released as an arcade game in 1987. A version for the Nintendo Entertainment System from American Sammy was released in 1989.

The original arcade flyer establishes that despite a 199X treaty eliminating all nuclear weapons, a certain northerly nation was suspected of developing such weapons in secret. Therefore, the United States of America military sends in the U.A.G. elite unit consisting of an armed motorcyclist and a support bomber to quell the threat.^[4] The American NES version's manual describes a slightly different story, casting players as a part of Operation Thundercade, a special forces operation battling against the nuclear threat of the Atomic Age Terrorist Organization of Miracali (AATOM).^[5][6]

Players control a motorcycle equipped with sidecar cannons and backed up by a B-7 bomber.^[5] There are four levels in the game: an unnamed city, the terrorists' military base, the woodland regions, and the fortress containing the nuclear power plant.^[6] Bosses include a submarine along with other screen-filling enemies.

In Japan, Game Machine listed Thundercade on their December 15, 1987 issue as being the seventh most-successful table arcade unit of the month.^[7]