Since the other reviews (so far) are only covering the very not good PC-88 & PC-98 ports, let's talk about the X1 original.

This isn't an amazing arcade shooter, at least not compared to Xevious or Star Force from the era. But it's a lot better than given credit, at least on Sharp X1 & MZ micros. I first got into playing this several years ago, each time warming up a bit more to how it plays. For comparison's sake, even the mighty Famicom wouldn't have any original STGs of this caliber & ambition until 1985 onward. Kotori Yoshimura built this turn-of-'84 tech showpiece all on her own, yet it's still fun if you like a more strategic open-range shooter. (I play this on an X1 emulator using cursor keys with no other enhancements or major changes.)

A big issue I see players having is keeping track of shots while landing your own, whether in air or on ground. Thankfully the game's soundscape, though sparse, makes enemy fire identifiable enough for quick dodging. Pay attention to the dull blips of enemy shots, and also keep a mental bead on where enemies are spawning. Certain foes will intercept you & lead shots better; they're usually a light pinkish-red in this version. I make sure to eliminate or avoid them as much as I can while bombing targets to find the real prize: the Dyradeizer bomb-ables.

It's possible to meticulously clear each stage, but the smart play for seeing more of the game (let alone clearing a loop) is to reach the stages' second phase quickly. Reaching the Dyradeizer side of each stage simplifies matters a lot since there's less dogfighting & more dodging turret fire. It's also simple to just destroy the Dyradeizer core ASAP if you're ready to proceed, rather than continuing to bomb out the rest. Getting through stages like this helps with learning movement & spawning behavior, which in turn makes playing for score much more manageable.

Enough strategy. What's the deal with Thunder Force on X1?! /seinfeld

I liken it to a long-lost pen pal of Raid on Bungeling Bay, but with more obvious Namco influences (ex. Xevious, Bosconian) and more impressive visuals. The X1 original uses the PC's built-in spriting hardware (the PCG chip) to handle stage objects & actors faster than any other PC STG of its time. This doesn't make it unplayable, but certainly zippier than you'd expect from a mid-era 8-bit micro. The simple control scheme, level progression, & enemy roster means it's easy to get started with Thunder Force. It's a very difficult game for sure, yet hardly a mystery. Maybe the enemy bullets could have been drawn more visibly, but they're readable enough after playing for 15 minutes.

The game's ports retain the solid game loop, particularly the scoring system & map/enemy variety, but massively lose out in other areas. (I'll exempt the MZ-1500 version here for being fairly close to X1 and arguably a better speed for some players who want to learn the game.) At that time, the PC-88 really couldn't handle this kind of game, even with the fastest pseudo-sprite coding in games like Kazuro Morita's Alphos. Surprisingly, even the more underpowered PC-6001 port feels better to play (and a lot more impressive) than that of its bigger cousin. And since the FM-7 release basically matches the PC-88 one, that makes for a poor but unsurprising showing. Yoshimura & her co-programmers had to make not just these ports in rapid succession, but tons of other quick ports during those pre-Mega Drive years at Tecno Soft. Rushed ports were common, and it's a travesty how many people get their first glance at this game via its less-than-representative versions.

One flaw that's always irked me is how the game handles shot collisions. You really have to commit to your own ground bombs, ex. not changing direction immediately while the shot lands, or else you risk not blowing something up. It's much less problematic with air fire thankfully, but hardly ideal. And there's the old problem of not being able to stop mid-flight, requiring you to manage your direction at all times. This leads to a lot of circular movement around parts of each stage if you're trying to destroy everything. Even I get a bit exhausted by this! But it's a matter of getting used to these weird physics & building your tactics around them. Pro tip: the game calculates enemy fire direction based on where you're flying when it's calculating their attacks. Use that to manipulate enemy fire away from you, then make your attack.

It's worth dealing with some odd collision detection & tricky enemy patterns for one of the best pick-up-and-play arcade originals defining the early J-PC software lineup. Yoshimura & her colleagues would proceed to form Arsys Soft a year or so later, where they made much better works like WiBARM & Star Cruiser. But games like Thunder Force showed her ability to evolve arcade-style play on a home platform—no mean feat at a time when Japanese PCs' hardware & developer support was more fragmented. Both as a history piece & a game today, Thunder Force on X1 is worth a shot if you like the rest of the series or want to experience how the early post-Galaga shooters began to evolve.

Also, I'm glad to say there's no quaint, irritating rendition of the William Tell Overture in this version. You can put on any music you'd like!