Thunder Blade is one of those mid-to-late 80s Sega arcade games that gets a bad rap. Like many of its brethren, this was because the home systems at the time weren't nearly powerful enough for faithful arcade ports. But while After Burner, Space Harrier, and even Galaxy Force reaped the benefits of re-releases on 32-bit and later platforms, Thunder Blade never got the same treatment.
It's a shame, of course, because the original arcade game is actually pretty cool. The concept was most likely born from one of the Sega developers catching Roy Schneider's Blue Thunder on TV one late night and decided to make a video game loosely based on helicopters shooting stuff. It runs on the classic Sega X Board, and uses the popular Sega brand Sprite Scaler technique for some pretty impressive effects. There are two distinct viewpoints - an overhead and an over-the-shoulder vantage point.
The overhead sequences are impressively unique because the view is slightly tilted, seeing your helicopter is technically angled towards the ground. Your arsenal includes both a machine gun and missiles, both of which have unlimited ammo - the only difference is their attack range. In addition to moving left and right, you can also raise or lower your altitude, scaling the ground back and forth with some impressively smooth animation. Just watching it in action is incredibly cool, especially after you've been shot down and take off back into the skies. Although you can't technically move forward and background on the screen, you can alter your speed, including a super fast turbo mode.
There are a number of cool effects at work here. Other Sega Scaler games like OutRun pulled off a bit of visual trickery by layering several identical tiles one after another, each positioned and scaled slightly different from the last. This gave the impression of a solid object, like, say, a canyon wall. Obviously the technique looks a bit cheesy in retrospect, but it's remarkable for the time. Due to the different perspective, Thunder Blade pulls off a similar trick - the buildings and mountains found through the games are also layered tiles, which move at different speeds as you fly past. Here, it gives an illusion of depth in a strictly 2D game, without any of the fancy use of polygons. Pretty clever! Additionally, when enemy tanks are shooting at you, they're technically shooting right at the screen, again adding to the sense of depth.
Partway through the stage (your progress is tracked by a meter at the top of the screen), the viewpoint changes to a more familiar over-the-shoulder perspective. They're pretty much just like the bonus stages of After Burner, in that it's possible to crash into the scenery if you're not careful. Here, the machine gun is used to take out airborne targets, while missiles travel along the ground.
When you reach the end, the perspective once again switches to an overhead view, although here you can't change you altitude. Your goal is to conduct a bombing run on a gigantic tank and/or jet, taking apart it turrets piece by piece. The only exception is the final stage, which ends in the over-the-shoulder perspective against a different type of gigantic tank.
It's a short game, with only four rounds, consisting of flights through a city, the wilderness (complete a harrowing flythrough of some caverns, where you need to skillfully dodge rock pillars), a canyon, and an oil refinery. It's pretty standard stuff, but like most Sega games of the era, the brightly colored pixel art is attractive, and it can't be mentioned enough that the scaling still looks incredible, even decades later. The music is appropriate 80s action music, with a significantly overwhelming amount of cowbell. It's rather unmemorable, since the explosions tend to drown it out, but it works well enough. Of course, like many other Sega games, the big draw of the arcade version was the sitdown arcade cabinet, so the home versions just don't have quite the same appeal.
The Sega Master System port obviously can't even come close, and doesn't even try, for the most part. The overhead scenes have been changed entirely to 2D, without the ability to change altitude or fix your speed, and any and all of the 3D effects have been totally removed. As such, it feels like a really standard, really boring shooter, especially since your firepower is so weak and there aren't any extra weapons. Strangely, most of the helicopters you fight don't attack fire any guns, and are content to fly in the same handful of formations, ramming straight through your copter in unnumerable kamikaze attacks.
The over-the-shoulder segments aren't much better. Naturally, they're pretty choppy, but the first one is remarkably boring because half of the enemies can't even damage you - they're just there for target practice. It gets more difficult by the second stage, where the choppy scrolling as you fly through the cave makes it quite hard to maneuver through them successfully. The levels are essentially the same, although the order of the bosses has been changed from the arcade game. The only positive aspect is the image of the burning, wrecked helicopter when you lose all of your lives. Otherwise, it's a total wash. Interestingly enough, the Japanese version usually a few different sound effects than the American/European version, which is a little less harsh on the ears.
There are numerous other ports for the home computers. Far and away the most accurate is the X68000 port, released by Sony in 1990. It's almost arcade perfect, other than some palette changes and a bit of slowdown. But since this was only released in Japan, Western gamers probably had to do with one of the many conversions published by US Gold. Most of these - for PC, Amiga, Amstrad and Commodore 64 - are notably impressive, because they actually contain the scaling in the overhead stages, which the console ports never bothered with. They're obviously not quite as smooth, and the tiles aren't as detailed - they're usually just a single color or two, depending on the version - but it's not bad, depsite the huge border on the top of the screen. The Amiga and Atari ST versions look the best, with some notably downgraded visuals in the DOS version. The problem lies with the controls - in most of these, you need to manually adjust your speed, otherwise you'll just hover in mid-air. In the Amiga version, for example, you need to hold down the fire button and press up to speed up, then press down to take off. It's remarkably unintuitive, and can lead to a lot of cheap deaths. The only version spared from this is the Commodore 64 version, which despite being one of the worst looking of the bunch, handles fairly well. The MSX version is just a quicky port of the ZX Spectrum version.
There were also two 16-bit ports. The Sega Genesis version was released around the launch of the system and is called Super Thunder Blade, despite there being nothing "super" about it. Their solution to the scaling in the overhead stages is to simply cut them out completely. Instead, each stage starts off in the over-the-shoulder segment. To make up for this, these stages now have a new mid-boss, similar to the one fought at the end of the arcade version. After defeating this, you go into an overhead view, but there's no scaling at all (which makes sense - you couldn't change altitude in these scenes either.) These play out pretty much the same as the arcade game. Once again, there are only four stages, with the first, second and fourth being roughly identical to the arcade game, and the third being a brand new level that takes place over the ocean. There's also a new final boss, fought in the overhead perspective.
That's all well and good, but the Genesis still chokes on the game. The 3D scrolling is better than any of the other ports, but it's still a far cry from the arcade game. Some areas look embarrassingly bad, like the caverns in the second stage. And someone had the bright idea to make your helicopter control like an actual helicopter - in other words, there's a split second of lag before every movement, which makes maneuvering through anything a massive bout of frustration. There's no ability to change speed either. Super Thunder Blade pops up in a lot of Genesis collections, like the Sega Genesis Collection for the PS2 and PSP, and Sonic's Ultimate Genesis Collection for the PS3 and Xbox 360, for reasons that aren't entirely clear. The latter compilation actually requires that you get a high enough score in order to unlock the arcade version of Space Harrier.
The PC Engine version, ported by NEC Avenue, actually keeps up all of the overhead sections. It removes the scaling, but as a compromise, allows the helicopter to move up and down the screen, which you couldn't do in Super Thunder Blade. Obviously, the buildings look a bit choppy, but it's better than just hacking out these segments altogether. The animation in the over-the-shoulder stages are smoother than the Master System version, but not quite as good as Super Thunder Blade. The distance meter is present - it's absent from the other console versions - but you still can't change speed. All things considered, it's a better port than either of Sega's console versions.
Comparison Screenshots - Overhead
Comparison Screenshots - Over-the-shoulder