A Shoot 'em Up series by Technosoft, which started with an obscure Japanese computer title in 1983 as a multi-direction overhead view shooter. It eventually become a side-scrolling shooter in the third installment, famous for its loads of Awesome Music.The Excuse Plot puts player in shoes of the GalaxyFederation's pilot in the Fire Leo starfighter against the overwhelming cybernetic ORN Empire. Thunder Force Vchanges the focus to Earth when Earthmen discover the wreck of Thunder Force IV's Fire Leo (Rynex) and reverse engineer it. The Guardian, an AI designed to study Vasteel (as Rynex comes to be known), however, goes haywire on humanity, but not before they create their own Vasteel starfighter. Thunder Force V is also known for having more story than the previous games, which ties together the events of IV. The sixth installment was trapped in Development Hell for a decade, but eventually released.The Thunder Force series spans six games:
Thunder Force (A variety of PC platforms, 1983) — The first game in the series, and the least well-known. Comprised entirely of overhead stages.
Thunder Force II (Sharp X68000, 1988) — Alternates between overhead sections and side-scrolling sections. Rereleased on the Genesis as Thunder Force II MD, with one less overhead-sidescroller pair and more balanced difficulty. MD itself was ported to Saturn via Thunder Force Gold Pack 1.
Thunder Force III (Genesis/MD, 1990) — Completely does away with overhead sections. Ported to the Saturn via Gold Pack 1.
Thunder Force AC (Arcade, 1990) — An arcade port of III (unusual in that ports generally go from arcade to console and not the other way around), but with altered 4th and 5th stages. Ported to the Saturn via Thunder Force Gold Pack 2, with an autofire feature that was not present in the original version.
Thunder Spirits (SNES, 1992) — A SNES port of AC (making it a port of a port), with a new stage 5 and stage 8. The least-known of the three versions of TFIII, despite being on the most popular platform of the three platforms it appeared on.
Thunder Force IV (Genesis/MD, 1992) — Released as Lightening (sic) Force: Quest for the Darkstar in North America. Ported to the Saturn via Gold Pack 2, with less slowdown and III's player ship as an unlockable ship.
Thunder Force V (Saturn, 1997) — The first game in the series with three-dimensional graphics, and introduces the Over Weapon system. Ported to the PlayStation as Thunder Force V: Perfect System, with less slowdown (but reduced visuals) and some omake content.
Thunder Force VI (PlayStation 2, 2008) — A whopping 11 years after the initial release of V and one failed attempt to bring it to the Dreamcast. Due to the low quality-to-anticipation ratio, it was not well received.
The Thunder Force series contains examples of:
A.I. Is a Crapshoot: Main plot of V. Humanity built a super computer named Guardian to study the wreckage of Rynex, the 4th game's Fire Leo. It then built a large fleet of starships based on the data. Then Guardian's AI damper program mysteriously disappeared and it turned against humanity with said fleet. Subverted. Guardian is still loyal to humanity. Faust (the Big Bad from the previous game) escaped its destruction by transferring its program to Rynex, which deleted the AI damper after Guardian accessed its history logs. In the end, Guardian reveals that it helped humanity by purposefully spreading its forces thin and leaving critical flaws in its tactics, allowing the protagonist, Cenes Crawford, to destroy the fleet.
Always Accurate Attack: The Free Range in V worked like this — anything entering the green wireframe area would be in for a world of (unavoidable) hurt.
And Now for Someone Completely Different: V initially comes across as this, as it's set around 22nd Century Earth, though the story reveals a considerable connection to the events of IV. Especially since Vasteel is Rynex and that the Guardian was compromised by Faust.
Bittersweet Ending: Thunder Force IV has the Rynex being crippled in the escape from the explosion following the defeat of Faust and being abandoned to drift in space, while the scientists of the Galactic Federation admit that sending it in the first place was a mistake in and of itself. It also hints at its incipient return. Yet they still have hope for humanity's future.
The "Good" Ending in VI made the ending of IV more sweet than bitter, hinting that the crew of Rynex not only was rescued by people of Earth but also found them to be sympathetic enough to warrant further contact.
V has Cenes Crawford, pilot of the Gauntlet/Vambrace, learn that the Guardian was on Earth's side all along, and that it did what it could to help her fight Faust, who was behind the corruption. Cenes destroys herself and the Vambrace so that another incident like that can not happen again. As it turns out in VI, however, ORN Empire ends up finding its way to Earth, forcing Earth to resurrect Vasteel technology.
In II, a siren plays when encoutnering a midboss in a horizontal-scrolling segment. A lower-pitched one plays when facing the stage's endboss.
In III, bosses are preceded by a siren and the word "EMERGENCY" scrolling across the bottom of the screen.
In IV, a siren sounds when a boss battle is about to begin.
In V: "ALERT! The enemy is (approaching fast) / (dead ahead)! Code Name: <boss name> - <boss description>".
In VI, you get a siren and your ship's computer alerting of the boss in Tangut, followed by the name and description of the boss, both in English and Mongolian.
Break Them by Talking: In the "Bad" Ending of VI, a message from ORN Faust is played calling for Earth's surrender. It contains many parallels with Guardian's Last Message in V, albeit using bleaker analogies to make its points.
Fan Sequel: Broken Thunder, released after V and before VI. The good news: Hyakutaro Tsukumo worked on the soundtrack. The bad news: It was so ill-received that it is theorized that Tsukumo's involvement with it was why he was left out of Thunder Force VI's soundtrack.
Fetus Terrible: The ORN Emperor in VI is an extremely ugly and monstrous infant with 3 eyes and varying number of irises in each of them. Apparently, the design was lifted from a character from a manga the project director had once drawn.
Final Boss Preview: IV had Versus at the end of the Battleship Raid level. Your team of ships try to destroy it and get their asses completely handed to them, forcing the remaining members of your squad to resort to giving you the Mid-Season Upgrade. Thankfully, you get your revenge in the final level.
Harder Than Hard: "Very Hard" in Thunder Force II for the Sharp X68000, "Mania" in III, and "Maniac" in IV and VI.
Hard Levels, Easy Bosses: Many bosses in III die within seconds of exposure to your weapons, especially the Sever. In contrast, the stages themselves have many deathtraps that demand twitch reflexes and R-Type-style memorization.
I Let You Win: The Guardian in Thunder Force V. Cenes Crawford in her last message even lampshades this by stating that had it not done so, the odds of just surviving those battles wasn't even in single digits.
It's Up to You: ORN's forces are so much greater than the Galaxy Federation's that if the Fire Leo fails, their regular forces won't stand a chance.
Subverted in IV where other Galactic Federation fighters team up with you to take on the Cerberus battleship before the trope gets played straight in the boss fight immediately following and for the rest of the game.
Subverted in V in that your character leads a squad of RVR-01 Gauntlets (named "Thunder Force", incidentally). Later on, after the battle at Babel only the protagonist takes on the Guardian as only one model of the RVR-02 Vambrace is operational; Cene Crawford's report mentions that her squadmates essentially drew straws.
Mecha Expansion Pack: Brigadine booster for Gauntlet and Vasteel Original's own much-bigger and much-more-bizarre add-ons in V; in VI, Vasteel Nocht would "mimic" player ships from previous instalments this way as well.
Also happens in IV where the Rynex starts off functionally similar to the Styx, but at the halfway point it gets fitted with the Thunder Sword and gains spherical CLAW drones that serve as capacitors for the Thunder Sword.
Multiple Endings: IV just changes what song plays during the ending depending on the difficulty, but V's ending is decided by whether you beat the final boss fast enough, and VI has three endings depending on what ship and difficulty you chose and whether you used a continue.
Recurring Boss Template: Gargoyle starting with III, and ORN Faust in VI. In addition, the Gaia Beast from the second game's third horizontal stage comes back as Dust Egg, the seventh boss of the fourth game. The main difference is that Dust Egg has a second, much more active phase where it rises up on some sort of tendril and lunges all over the place.
Single-Biome Planet : The sole exception is V, which occurs on Earth. The ocean planet in VI is justified; it's a post-global warming world and you will get to pass the submerged city at one point. The jungle is really an abandoned space colony, with overgrown forests having overtook residental area.
Space Zone: VI plays with this by having the background move around with no effect on gameplay at times.