Thunder Force AC

Thunder Force AC was produced by Sega/Technosoft in 1990.

The gameplay is simple but challenging: shoot or be shot down. You start with TWIN SHOT and BACK SHOT, which can be selected during gameplay. By shooting down the power-up ship, you receive different power-ups. They are as follows:
Saber S: upgraded Twin Shot
Lancer L: upgraded Back Shot
Wave W: weak, wide shots that penetrates through walls
Firebomb? F: drops bombs that trail across ceilings and floors
Hunter H: three-way, fairly weak homing shots
Shield blue S: provides temporary damage protection
There are also two CRAW units mini-ships, which can be collected, that circle around your ship for extra firepower and provide some form of protection.

Thunder Force AC is a modified version of Thunder Force III made specifically for the arcades with reworked graphics – although still very close to what the Genesis was able to offer. Thunder Force AC puts you behind the cockpit of a lone starfighter out to destroy all the enemy forces of the Orn empire by clearing 8 enemy-infested stages set in various outer space locations. Most of the game levels are taken directly from the Genesis version with a few minor changes, though levels 4 and 5 are totally different – both in graphics and level design.

The game gives you a health-bar and the ability to swap collected weapons on the fly, which can be obtained by catching power-ups and activating them whenever you want.