Thunder Force III

Thunder Force III (サンダーフォースＩＩＩ) is a side-scrolling shoot 'em up video game developed by Technosoft as the third installment of the series. It was released in 1990 for the Sega Mega Drive/Genesis console and was ported to arcades under the name Thunder Force AC, which was in turn ported to the Super Nintendo under the name Thunder Spirits.

The game takes place directly after Thunder Force II, 100 years after Thunder Force. The ORN Empire has hidden cloaking devices on five planets, obscuring the location of their true base. They have also constructed a remote defense system named Cerberus that is specifically designed to destroy large ships and fleets. To counter this, the Galaxy Federation creates the FIRE LEO-03 Styx, a ship small enough to avoid detection by Cerberus yet containing the firepower of a larger ship. Styx is deployed on the five planets to destroy the cloaking devices, infiltrate the Empire's main base, and destroy its supercomputer, "ChaOs".