It says Invalid Serial Key

[Kiberabobus]

I played the game a lot but since I got a new version of Windows and had to redownload the game when I just started it up it says I have to enter the serial key. Which I did, but it says the key is invalid for some reason. I tried reentering it several times and it still doesn't work. And now I can't play the game at all. Does anybody have a fix?

[Aquila]

Is your game original?

[Kiberabobus]

Of course it's original, it's on Steam, Steam gave me this key.
This is a really old post,
in the meantime I did two complete reinstalls of Windows and on the second one upon reinstalling Earth 2160 it worked fine
Still, it's unusual that the game would not accept my legit code