If you're a joystick hero and your 3D thinking is top notch - you KNOW this game, you PLAYED this game, and you OWN this game. Not sure why anybody would buy this on GOG unless they messed up their game discs. Hint: Although it does not rub it in your face, the game usually runs berst on OpenGL (wise move), not DirectX.
If you're a joystik hero and your 3D thinking is NOT top notch ... heh, just use Wingnut, your all-knowing /renamable) cheatbot included in every edition of the game [lol].
Features two engines (outside and inside) seamlessly stiched together for a nice experience. Gawd, it's great :]