There are 8 levels in Thunder Spirits, each consisting of the ship battling numerous enemies while side-scrolling, usually with a "mini-boss" about halfway through the level. Then, at the end of each level, a boss (consisting of one or two enemies) appears, which must be defeated before proceeding to the next level. Throughout the level, the ship can pick up "Weapon upgrades"; and the player is able to switch between any of up to 5 weapons at any time. The game is part of the Thunder Force series. It is a port of the dually copyrighted Technosoft/Sega arcade game Thunder Force AC, which itself is actually a modified port of the Sega Genesis game Thunder Force III.