Apparently something is supposed to happen if you run the game after completing it. It didn't work for me though. Should i have run it as administrator the second time?

I think you should always run the game as administrator, but an easy way to tell if you actually completed it or not (the windows file sometimes bugs out like that) is to go to your Program Files folder (C:/Program Files) and check to see if there is a file named: Closed.txt

If that file exists then it worked, otherwise, just make it yourself, the game doesn't care about the text inside it I believe. It's an easy way to skip the game and get to the special one!