Ow. That was painful to follow.
To explain better... read
http://www.hardcoregaming101.net/valis/valis.htm , or I'll just list all the Valis games below.
The first version was in '86 and was for some Japanese computers (MSX, NEC PC88). Apparently the gameplay is something like the later titles, but worse, and without much story. Japan only game of course.
Next came a NES version, in '87. This one's got large mazelike levels you have to explore around (though still side-scrolling as always). It was only released in Japan, and is also supposed to be bad.
Next came Valis II for Japanese computers (MSX, NEC PC88, and X68000), in 1989. HG101 says that it's okay for the time. I wouldn't know. The last of those three versions is surely the best by far, given how much more powerful the X68000 is than those other two systems. It's apparently the first Valis game with much story in it, and it has an armor-switch system.
Then came Valis II for Turbo CD, also in 1989 in Japan (1990 in the US). It's alright. Decent game, though frustrating as always for Valis titles. It's got full voice acting in the cutscenes, and CD music of course. The armor-switch system was removed, though.
Next was Valis III for Turbo CD, in 1990 in Japan (1992 in the US). It's decent, probably better than the second one. This time there are three playable characters. A Genesis port of the game followed in 1991, without the CD music and voice acting of course, and with some other cuts as well (I think it has fewer levels as well). This released in March '91 in Japan. HG101 says that this released after the Valis 1 remake, but they're wrong, it was the other way around, in Japan at least, and probably in the US as well.
Also in 1991 (in August), they released Valis IV for the Turbo CD. This game was only released in Japan, unfortunately. It's one of the better Valis games. The game has four playable characters, including the only male playable character in the series (it's this giant alien-like guy).
Next was a Genesis remake of the first Valis game, in the style of the newer titles. This released in 1991. I think the game has the same basic story as the old Valis version(s), but the gameplay and levels are of course new, and much better than previous Valis 1 versions. This released in December '91 in Japan.
In 1992, in February, in Japan, they released a superdeformed remake of Valis II for the Genesis. The game was called "SD Valis" in Japan, and "Syd of Valis" in the US, with Yuko renamed to "Syd" here. Ah, localization... The game has different level designs from the earlier versions of Valis II, and puts back in the costume-switch system for Yuko, still with the same basic story. It seems easy at first (you just bounce in pits and take damage, instead of dying, for example), but you've got no continues here, so you will need to be decent to finish it.
In March 1992 in Japan, and about a year later in the US (so early '93), a SNES remake of the game was released. This version has all story scenes except for shortened intro and ending scenes cut out of the game (including in the Japanese version), and drops three of the four playable characters too; instead you have only one character, but can collect multiple different special weapons and abilities which you can collect and switch between instead, which is nice. I miss the other characters though, even so. The levels are longer in this game than the Turbo CD game as well.
Finally, also in March 1992 in Japan and sometime that year in the US, Telenet released an enhanced (and Japan-only) Turbo CD port/remake of the Genesis remake of Valis 1. This is the only Super CD Valis game for the TGCD. It's also the only one of the four that doesn't let you save your progress; the earlier three do let you save, but this one copies the Genesis games and makes you play it in one sitting. Unfortunate. The gameplay's as good as you will find in the series though, though that is mixed praise for sure, but it is better than some of the Valis games anyway. And that was it, as far as actual games are concerned.
In 1993 they released some Turbo CD collections of Valis cutscenes in the Valis Visual Collection, but those didn't have any actual gameplay. That was it for the franchise, apart from some "Valis"-themed hentai visual novel games released many years later.
