


Airgrave (PS1, Santos 1996)
http://youtu.be/PMfRbWNux5E
(Classic YouTube Reviewer: "There's bad guys causing trouble and you've got to shoot them up, which will cause them to explode." Yeah, thanks for that.)
Stahlfeder (PS1, Santos 1996)
http://youtu.be/s-U6dCNJZ8Q
Two-Tenkaku (PS1, Sony Music Entertainment Incorporated 1995)
http://youtu.be/C7K1Ds7Rioo
All three games look and play fairly alike - they're all vertizontals (everyone's favourite!) and they're all a bit rough around the edges. Visually, they look a bit like Giga Wing, only uglier. And Giga Wing isn't exactly the prettiest game to start with...
Stahlfeder is probably the most straightforward in terms of gameplay. You've got your basic spread fire, laser, plus bomb; the scoring system isn't too sophisticated, and it's also fairly easy. There are some ugly polygonal graphics - check out the boss at 9 minutes in the video, which I'm pretty sure is directly copied from the Stage 1 boss in Brave Blade. Maybe they thought that, since hardly any plays Brave Blade, no-one would notice.
Airgrave adds a lock-on attack similar to Soukyugurentai, although it's not particularly well implemented and seems a bit fiddly to use. If you do get the hang on it, though, it seems to add a bit more in the way of scoring potential than Stahlfeder, so there is that.
Two-Tenkaku probably has the most to offer in terms of visuals - it's still ugly, but it has a wacky mix of enemies and backgrounds that are a bit more original than the usual mix of planes and tanks. Plus, there are some heroically bad FMV sequences between levels to keep you entertained. One of the later bosses kinda reminded me of something from Jamestown, only uglier, obviously. It does make the mistake that vertizontals sometimes do with bullet patterns; i.e. the boss takes up half the screen and its bullet patterns start from near the bottom of the screen, giving you very little time to see what's coming. e.g. the boss at 4 minutes in the clip. Also, while you can have a normal shot button and a 'rapid' button, the rapid button is pretty useless, as it only fires a burst of 5 normal shots. So you have to mash whichever button you decide to use...
So, they're all fairly generic and don't have too much to offer, but I'd say they're mediocre rather than really terrible. If you're going for one I'd say pick AirGrave if you want a bit more scoring depth (relatively speaking); pick Stahlfeder if you just want a playable Raiden-esque game which is pretty easy to blast through; or pick Two-Tenkaku if you want some slightly more original visuals while you're playing what mainly amounts to the same game.
If you're keen on tracking down the actual discs...none of them are particularly cheap. I did see copies of Stahlfeder on sale in Akihabara for about $25-30, but it seems to go for even more on eBay. I'm not sure it's worth it...