Thunder Force IV is a horizontal shooter created by Technosoft for the Sega Megadrive/Genesis in 1992. It is the sequel to Thunder Force III and the prequel to Thunder Force V. In the US, it is called Lightning Force: Quest For The Darkstar.
Adapted from the US manual:
In the Galactic Standard Year of 980, The ORN Emperor declared war on the Unified Federation of Galaxies, known as the Galactic Federation. After a long struggle against the ORN Empire, two extraordinary pilots, in the legendary Styx Fighter, managed to destroy the Orn Control Ship and stop the Empire in its tracks.
The ORN Empire's main computer system, supposedly destroyed in the battle, was actually only damaged. The still-functioning mainframe data was retrieved by one of the Orn's allies, the Kha-Oss Legion, and is being rebuilt on the planet Vios.
Should the information in the computer be analyzed, it may show weak points in the Galaxy Federation's defenses. If this happens, the ORN Empire and the Kha-Oss Legion will certainly move against the Galactic Federation again.
You have been chosen to lead the battle against the forces protecting the Orn computer's mainframe data, in a desperate attempt to save the Federation from destruction. You mustn't fail!
The Reign of Kha-Oss
Your mission has two sections: First, you have to lead the attack on the main military planet of the Kha-Oss Legion. Once this planet's offensive weaponry has been destroyed, the Galactic Federation will be able to launch an offensive against the inner planets in the Kha-Oss system, knocking out their command center. Their military will be at a disadvantage if they lose their main computer banks.
Your next mission will be to travel to Vios and search for the ORN Empire's main battle computer. Knocking out the military planet will make it easier to penetrate the inside of Vios. If the Federation is able to destroy the ORN Empire's main computer database, peace in the galaxy can be assured.
There are four areas in the first part of your mission. Destroy the military equipment that the Kha-Oss Legion is building up, and then take on the main battle cruiser. There will be other Federation spacefighters there to help you.
The gameplay is just like the previous Thunder Force games. This time, the fighter being used is the Fire LEO-04 "Rynex". The starfighter is equipped with two weapons by default, but can receive more upon shooting down carriers.
- Twin Shot - A twin stream of rapid firing energy shots are unleashed directly in front of the fighter. This is one of the initial weapons and cannot be lost upon death.
- Back Shot - A single stream of rapid firing energy shots are unleashed in front and back of the fighter. This is one of the initial weapons and cannot be lost upon death.
- Blade - An upgrade to the Twin Shot, this shoots out rapid firing energy blades in front of the fighter.
- Rail Gun - An upgrade to the Back Shot, this shoots out two powerful lasers in the rear of the fighter.
- Snake - This napalm bomb shoots directly up and down. Upon impact, a stream of explosions traverses the ground. A single energy stream is also shot in front.
- Free Way - This weapon can fire in any direction, firing in the opposite moving direction of the fighter. It shoots a five shot 45 degree fan of missiles, with 1 missile shot in the ends, 2 in the median, and 3 in the middle. Also, a energy stream is shot backwards of the main fire.
- Hunter - This weapon is exactly like the Hunter from Thunder Force III. Energy balls are shot in a rapid three-way stream and homes in on any enemy on screen. They are not too powerful but very accurate.
- Claw - A twin pod support unit that adds to the Rynex's firepower and acts as a makeshift shield as it is able to block some enemy shots.
- Upgraded Claw/Thunder Sword - The Claws are upgraded and enable the Rynex to shoot the powerful Thunder Sword. This is done by not firing and wiating till electricity surrounds the Claws, then firing. One must be careful when using it as the fighter will be pushed back a little from the force of the blast.
- Shield - A shield surrounds the Rynex and can sustain three hits before dissipating.
The first four stages can be done in any order.
- Stage 1 - Strite
- Boss - Gargoyle Diver
- Stage 2 - Ruin
- Boss - Hell Arm
- Stage 3 - Air Raid
- Boss - Ratt Carrier
- Stage 4 - Daser
- Boss - Fomalhaut
- Stage 5 - Vios, the Space Cruiser
- Boss - ORN Faust
- Stage 6 - Volbados
- Boss - Spark Lancer
- Stage 7 - Desvio
- Boss - Dust Eag
- Stage 8 - Wall
- Boss - Evil Core
- Stage 9 - Bio-Base
- Boss - Armment Clow
- Stage 10 - Versus
- Boss - ORN Faust, Vios Computer (Khaos)