Big Fish games have to be activated online through the Big Fish client or they will play as demos, and run out after 60 or 90 minutes (depending on length of demo).
If a game has previously been activated on the Surface, then uninstalled, it will still remember the previous activation if the game folder is copied back over to the Surface. If the game was not previously activated, it will play as a demo.
If the internal WiFi on the Surface went bad, and it has a USB slot, you might be able to use a USB WiFi adapter.