Although SNES fans will insist that Nintendo's 16-bit powerhouse had a more diverse range of software when compared to its bitter rival the Mega Drive, one genre in which it simply couldn't compete was the 2D shooter. Sega's console was quite literally flooded with top-notch arcade blasters and one series which is particularly worthy of praise is Technosoft's legendary Thunder Force. Despite not being a first-party Sega release the franchise would become almost synonymous with the Mega Drive and was responsible for converting a great many gamers to the platform.

However, prior to the eyeball-searing visual excesses of the Mega Drive instalments Thunder Force established itself in the rather more mundane arena of Japanese personal computers. "Before they started developing for consoles, Technosoft primarily created software for the various Japanese home computer systems such as the Sharp X1 and the NEC PC range, and the original Thunder Force was one of these games," explains highly-knowledgeable shooter enthusiast and Hardcore Gaming 101 contributor Paul Brownlee. Surprisingly, this debut title showcased very few of the features which would make the franchise so beloved with shooter fanatics; in fact the gameplay was viewed from a top-down perspective and was very different from what would follow later.

"Technosoft also released a Thunder Force construction kit which let you create your own stages"

"You fly over different landscapes armed with an airborne shot to attack flying enemies and a ground bomb to destroy structures," Brownlee reveals. This mechanic made the game a very close match to the coin-op hit Xevious, which has led many to surmise that Technosoft was heavily inspired by Namco's influential title. Because the game was designed for Japanese computers, few western gamers have had the opportunity to sample it. "I've only seen the Sharp X1 version first hand but it was released on other computer formats, such as the Fujitsu FM-7 and NEC PC-9801," explains Brownlee. "The visuals and features between each version depended on the power of the hardware it was running on. After the initial release of the game, Technosoft also released a Thunder Force construction kit which let you create your own stages."

It was hardly the most inspiring start for the series but Thunder Force nevertheless found an audience amongst action-starved Japanese PC owners. It wasn't until the inception of the sequel – which was programmed for the Sharp X68000 personal computer in 1988 and converted to Sega's newly-launched Mega Drive console the following year – that Technosoft's most famous brand got a release outside of Japan. However, while the second title may be notable for bringing the name to western audiences it isn't viewed as kindly as its successors, largely due to the fact that it mixed brand-new side-scrolling levels with the overhead stages found in the original release. "Most of the complaints about Thunder Force II come from top-down stages, while the side-scrolling levels tend to be viewed in a more positive light," says Brownlee. Although the Mega Drive edition of the game would achieve a global release it was actually a port rather than an original production. "It's not commonly known but Thunder Force II was developed for the X68000 first and converted to the Mega Drive afterwards," says Brownlee. "The Sega edition lacks several features present in the original. For the top-down stages there was a handy map which would show the approximate location of the enemy bases. It also had extra stages which were removed from the Mega Drive port. Other things present in the X68000 version were an extended intro sequence with a narrative, some extra graphical effects, different weapons, better music and much clearer voice samples – amusingly, the game blurts out an expletive when you lose your last life, as if the game knows what's on the tip of your tongue when it happens."

Despite the criticism directed at the top-down levels Thunder Force II still managed to find favour with many Sega players, thus encouraging Technosoft to expand the series further. For the third title the company wisely decided to focus solely on the much-loved side-scrolling viewpoint and abandon the overhead perspective altogether. This savvy move – combined with some astonishing visual tricks and suitably hectic gameplay – would result in one of the most significant Mega Drive games of the early '90s. "At the time of Thunder Force III's release in 1990 the Mega Drive was just starting to pick up its stride and showcase itself as markedly superior to the NES, Master System, or any other last-gen console," Brownlee recalls. "People were overawed by the famous wavy fire background effect of the lava level; its fluidity was unlike anything they had ever seen up until that point. It also had the benefit of being released around the peak of shooter popularity, at that time people were much more receptive to the genre." Thunder Force III was also responsible for establishing the reputation of the series for awesome chiptune rock soundtracks; the intense background music was the perfect companion to the dazzling on-screen action.

"Thunder Force AC was ported to the Super Nintendo as Thunder Spirits which again was mostly the same but had some slight alterations... The battleship stage is completely different and a portion of the final stage where you fight the last boss has been tinkered with slightly"

Thunder Force III was so successful that it warranted an arcade port – which is ironic when you consider that most shooter franchises tend go in the opposite direction. "Thunder Force AC is essentially the same game as Thunder Force III but with a few changes," Brownlee explains. "Thunder Force AC was ported to the Super Nintendo as Thunder Spirits which again was mostly the same but had some slight alterations from its arcade counterpart. In particular, the battleship stage is completely different and a portion of the final stage where you fight the last boss has been tinkered with slightly." The SNES has a poor reputation for shooters due to its slow CPU and Thunder Spirits predictably suffered from crippling bouts of slowdown.

After the insane graphics of the third entry many fans believed they had witnessed the zenith of genre but Technosoft would quite literally blow away its followers with the next entry. "Thunder Force IV is one of those games where every aspect comes together perfectly to deliver something extraordinary," gushes Brownlee, leaving little doubt as to which entry in the franchise is his personal favourite. "I think this game is the best at demonstrating how much Technosoft mastered the Mega Drive hardware; it was really the platform on which they peaked. The quality of the graphics is immediately apparent from the first stage, where you can see the multi-parallax scrolling effect in the water and the landscape in the background. You can scroll vertically across a two screen lengths for the first stage and several of the others, which makes the playing field seem open and gives things a greater sense of scale.

Of course, you can't really talk about Thunder Force IV without mentioning its music. Technosoft games have a reputation for good tunes and the company was extremely skilled at making the Mega Drive sound chip produce brilliant melodies, despite it being seen as inferior to the Super Nintendo's sound hardware. Again, this is the game that demonstrates Technosoft's prowess the most, as many people remain impressed with the soundtrack from not only a musical standpoint, but from a technical one as well." However, despite the incredible achievements made in the game, Brownlee thinks that the perfectly-balanced challenge was arguably just as significant in making it such a success. "Most Thunder Force games tend to be on the easy side," he says. "However in the fourth game the default difficulty is challenging but not overly difficult. On that note, the bosses in Thunder Force games have a bad habit of being pushovers, appearing as intimidating threats in their intros, only to go down after few sprays of your weapon in an anti-climactic fashion. Refreshingly, most Thunder Force IV bosses are an exception to this rule and will not only put up a fight but take a good amount of punishment. Finally, I love how they give you a devastating new toy to play with halfway through in the form of the powerful Thunder Sword, because it reinvigorates your interest."

Thunder Force V took the series into the realm of 3D graphics, but the action remained in 2D

The series then endured a relatively prolonged absence following the fourth instalment; hardcore fans would have to wait five agonisingly long years before the next release. To keep them sated Technosoft released the Thunder Force Gold Packs on 32-bit Sega Saturn which featured ports of the original games. "The Gold packs were released in the mid '90s to drum up interest for the incoming Thunder Force V," explains Brownlee. "Gold Pack 1 contains the Mega Drive port of Thunder Force II and Thunder Force III while Gold Pack 2 contains Thunder Force IV and Thunder Force AC. Notably, the version of Thunder Force IV in Gold Pack 2 is slightly improved over the original as it eliminates the slowdown and contains an added Easter egg that lets you play as Thunder Force III's Fire Leo-03 Styx fighter."

"The graphics seem to have been more impressive at the time of its release, but like many pioneering 3D games of that era, they certainly haven't aged gracefully... I think it's a solid entry into the series, but it seems like a step down from Thunder Force IV "

As welcome as these retro-themed collections were, it was clear that they were merely the appetiser for what was to come. Thunder Force V was released on the 32-bit Sega Saturn (followed a year later by a port on the Sony PlayStation) and would drag the brand into the realm of 3D, with largely mixed results. "The graphics seem to have been more impressive at the time of its release, but like many pioneering 3D games of that era, they certainly haven't aged gracefully," admits Brownlee. "I think it's a solid entry into the series, but it seems like a step down from Thunder Force IV and feels very close to the third game. It does a pretty good job of making things seem fast and exciting and has some pretty sleek mechanical designs with the ships and bosses. Another big plus is the music; even today the soundtrack is a shining example of great synth-rock."

The fifth entry was significant in other ways, too; it incorporated massive changes in the weapons system. "Thunder Force V introduces the 'Over Weapon' system, which is kind of an expanded concept from the Thunder Sword in Thunder Force IV. In order to utilize these weapons you need to collect up to three energy satellites that rotate around your ship; each one acts as a power battery for the Over Weapon, in addition to enhancing your current weapon. As you use the Over Weapon, the satellites will drain until they reach a weakened state. In order to keep using your Over Weapon you either have to wait for the satellites to replenish over a short period of time or replace them with new satellites. Once weakened, the satellites will be destroyed if they are hit by enemy fire. Each weapon in the game has a more powerful Over Weapon version that you can use at will as long as you fulfil the previous requirements."

Although the PlayStation version of Thunder Force V was released after the Saturn edition and contained bonus features, it isn't considered to be the superior of the two by many fans. "The Saturn version contains some graphical effects that weren't possible to reproduce on the PlayStation and ends up being the better-looking of the two," explains Brownlee. "The Sony version can be seen as a 'Director's Cut', as it expands upon the original Saturn release with some in-game extras. Among them are added CGI sequences, a picture gallery, boss rush mode, hidden selectable variations of the main ship with different gameplay changing attributes and other minor touches. The core gameplay differences between the two are relatively minor, reduced to scoring and slowdown instances. Arguing over which one is superior has become an intense discussion amongst fans."

2008's Thunder Force VI was developed and published by Sega, as Technosoft had effectively ceased to exist by this stage.

Although they didn't know it at the time, these very same fans would have to wait almost a decade before they would play another Thunder Force title. Technosoft's fortunes took a nosedive around this time and development on the sixth game – which was supposed to be coming to Sega's newly-launched 128-bit Dreamcast console – was canned when the firm was sold and effectively disbanded in 2001. However, during these wilderness years a few events kept the magic of the brand alive. "After the sale of Technosoft the music composer for Thunder Force V released an album entitled NOISE Game Music Vol. 3 – Broken Thunder that featured some music that was intended to be used in the cancelled Thunder Force VI," says Brownlee. "He later re-released the music along with some past Thunder Force arrangement tracks under the music group he was part of at the time with the name Broken Thunder - Project Thunder Force VI. All of this cumulated in the group making their own fan-created Thunder Force sequel called Broken Thunder. Unfortunately for them, this unofficial sequel didn't go over to well at release and was mocked for being of poor quality, and this ultimately caused the group to dissolve."

"After the Technosoft was bought out and incorporated into Twenty-One Company – which manufactures pachinko units - most of its developers moved on"

While that attempt at keeping the series afloat might have been unsuccessful, Thunder Force managed to score a cameo role in what must rank as one of the most bizarre and downright brilliant Dreamcast games of all time: SegaGaGa. A Japan-only release which saw the player controlling the fortunes of Sega's development division, the game boasted a level which paid homage to Technosoft's seminal series. "The very last stage of SegaGaGa is a shooter sequence similar to Thunder Force where the boss takes the form of different Sega consoles," explains Brownlee. "Some the background music can be heard in the Broken Thunder albums and there are a few other extra Thunder Force-related Easter eggs in the game itself, including the CG video intro to the cancelled Thunder Force IV. Apparently, SegaGaGa director Tetsu Okano was a big fan and was able to sneak all of this stuff in."

Okano's ability to cram these references into his game set the wheels in motion for a proper sequel which would appear on the PlayStation 2 in 2008, with Sega handling both the development and publishing duties. The Technosoft moniker appeared prominently on the packaging, but the company itself no longer existed. "After the Technosoft was bought out and incorporated into Twenty-One Company – which manufactures pachinko units – most of its developers moved on," says Brownlee. "The company webpage remained stagnant for several years until it suddenly and quietly announced the return of the Thunder Force series. Shortly after, it was discovered Twenty-One Company had licensed the name to Sega because Okano was interested in making a sequel for the PlayStation 2."

Despite the initial excitement, many fans feel that this follow-up fails to fully capture the essence of the series. "It's not terrible, but I can't help but feel a little disappointed with it myself," admits Brownlee. "The obvious thing is that it's technically a Sega game and not a Technosoft title. One issue is that it's over with too quickly; the first few stages come and go before you realize it. Another problem is that your arsenal is overpowered and the opposition just doesn't seem to pose any threat whatsoever because of it. Two out of the three selectable ships start off fully powered up and don't lose any of their potency upon death, so there's little risk involved. I think this lack of penalty takes away a fundamental aspect of playing Thunder Force game: taking care when switching between your weapons so that you don't lose them in error. All of this results in a game that is very easy game to finish on default, but makes the experience lacklustre since there's no urgency or passion involved. I do feel it was too focused on paying homage to previous Thunder Force games and didn't really bring enough to the table to carve out its own unique place in the lineage."

"Other popular shooters appeared first in the arcade. Thunder Force had much humbler and obscure start on Japanese computers"

Thunder Force has always been sidelined when compared to fellow classic shooter series purely because it possesses a cult appeal; casual gamers will recognise the names R-Type and Gradius even though they may never have experienced those titles, but Thunder Force doesn't have the same resonance. Brownlee thinks this is partly due to the modest origins of the series. "Other popular shooters appeared first in the arcade, which was known as the place where the new and cutting-edge games were to be found," he says. "Thunder Force however, had much humbler and obscure start on Japanese computers. I'm willing to bet that people outside of Japan hadn't even heard of Thunder Force until the Mega Drive sequel came seemingly out of nowhere. Even today, many people aren't aware that Thunder Force I even existed. Another secondary reason for Thunder Force's lesser popularity could be because it liberally borrowed elements from more celebrated shooters so some may see it as an 'also ran' series. It some respects this is valid, but Thunder Force refined itself enough to gain the attention of a niche following."

Indeed, Technosoft's finest hour has gained the admiration of many skilled players, and Brownlee isn't at a loss to explain why that is the case. "I've always been a big fan of shooters in general, but I was particularly attracted to Thunder Force because it blends the memorization and obstacle-based design of the traditional shooter with generally faster pasted gameplay, so you get a better sense of speed and more adrenaline-filled moments than you would through a slow ponder in an R-Type game for instance. I think the games successfully combined solid gameplay with great aesthetics and presentation, as well as excellent soundtracks." It may not have the cachet of its 2D rivals but the Thunder Force moniker continues to live on in the hearts of its followers, and the news that Sega now owns all of Technosoft's IP – and that is has remastered Thunder Force III as a 3D Classic on 3DS – bodes well for fans of the series.

This feature originally appeared in its entirety in Imagine Publishing's Retro Gamer magazine, and is reproduced here with kind permission.