Although the original PS1 game Alien 4: Reborn from Fire never appeared on PC, PC players can use the ePSXe emulator to experience it. Now the former Argonaut Games developers have leaked several earlier versions.
Interestingly about Alien 4, the game was originally a top-down view game, similar to Loaded. Then, during development, Argonaut decided to turn it into a third-person action-adventure game. Finally, the game changed style again and was released as an FPS.
This is reminiscent of the development of Halo. Halo started out as a strategy game. Bungie then transformed it into a third-person action game. However, the game once again switched style to become a first-person shooter.
Interested players can download earlier versions from here.