Thanks for the input, guys! Very interesting stuff. I have The Raiden Project for PS1 (it was actually one of the first games I picked up for the PS1 bitd and I've luckily held onto it all these years) but whenever I find a version of it on the cheap out in the wild I have to pick it up. I agree that it is the best version out there. Once upon a time I had the Turbografx version, but it was stolen along with all my other turbochip games and my Express back in the 90s when our house was broken into.
It's been awhile since I've played Raiden on any system, and I've been playing a lot of Kyukyoku Tiger these past couple of months, so when I popped in Raiden this evening, I felt a sense of de ja vu.
You're right, ccovell; it looks like Kyukyoku Tiger was originally released in 1987 and Raiden was released in 1990.
I fondly remember playing one of the Raidens at my local ice skating rink back in high school, but had never heard of Kyukyoku Tiger until recently. I didn't realize it was also called Twin Cobra here in the States, but I don't remember playing that in the arcades either.
I'm really surprised there are so many similarities between these games without the developers being the same. I would have at least thought that a bunch of the original developers left Toaplan to create Raiden. (like the makers of Torchlight did - a lot of them were the original developers for Diablo)
EDIT: When I play The Raiden Project on the PS1, I usually end up playing Raiden 2, that purple laser weapon is awesome!