Hi!
I am also one of those who found this website because of my incessant web search for this game I used to play when I was a kid. I used to play it on Windows 95, although I reckon it may be from 1998 or even 1999. I don't remember much of it, but I know it was kind of an action game. You had to control a character, human I think, who would transform into a spaceship to shoot enemies. I don't remember if this was the only way to do that, but I certainly remember having to transform into a spaceship. I think that as levels went by, you would unlock new and more powerful spaceships. This WASN'T a shooter, it was a side-viewed action game. Most of the time you would use your normal character to walk on solid surfaces. The environment was quite "futuristic", if that means anything. I personally remember a level which had a lot of blue and on the background you could see wires and chips and things like that. When I think of the game I always think of the color blue, maybe the character was also blue, although I can't be certain. My brother says he remembers a level in which the background had a lot of orange.
I know this isn't much, but it's the best I can do. It was a side-viewed 2D or a lame 90s 3D game, with a lot of pixelated shadows.
Can someone help me here? I honestly don't remember how I got the game, I think it was on a promo CD that came with a magazine but I'm not sure.