First off. This happened because you tried to open a *.package file in Chrome. You should not try to open these files as that is not how they work.
That said it doesn't really matter that the icon changed they will work fine in the game anyway. However you can reset file associations if you want to by going to Settings | Apps | Default Apps. Where it says "Reset to Microsoft recommended defaults" click the Reset button. Warning this resets all file associations which means that you may have other programs installed where you will need to setup the correct associations again.
Happy gaming.
I have the same problem but I'm on a Mac. I don't have the same settings, what should I do?
Ask in the Mac specific group how you do there but as I wrote it is not really necessary.
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