Thunder Force III (サンダーフォースIII) is a 1990 scrolling shooter game developed by Technosoft for the Sega Genesis.

The final new addition is that the player's ship now has a speed setting, which can be increased or decreased across four levels at the press of a button.

ORN has installed cloaking devices on five major planets in their space territory that conceal their main base, making it difficult for the Galaxy Federation to locate and attack their headquarters.

Also, ORN has built a remote defense system to protect itself named Cerberus, which is especially efficient at neutralizing large ships and fleets.

Knowing this, the Galaxy Federation creates the FIRE LEO-03 Styx; a craft small enough to avoid detection by Cerberus, yet equipped with the firepower of a large starfighter.

Ported to Sega's System C-2 hardware, Thunder Force AC is almost graphically identical to its Mega Drive counterpart, with only very minor and often unnoticeable differences.

GamePro called it "a straightforward flying shooter with gorgeous graphics", particularly mentioning the large, detailed enemies and "intricate backgrounds".

[4] In Japan, Game Machine listed Thunder Force AC on their February 1, 1991 issue as being the sixteenth most-successful table arcade unit of the month.