songsmith2003: I had the original version of this game and later replaced it via Steam on a sale. I was pretty miffed to find out I still had to go through EA's Origin to play it AND register on their old Spore site which EA does not maintain. Did GOG change this? Thanks.
Petrell: According to blues, GOG version is fully playable offline. You also get keys for redeeming game on origin in case you want to be able to import other players' creations.
To be fair, the Steam version can be fully played without connecting to its online features too. You only need to register if you want the game to automatically download user created content or you want to upload your own content. That said, I could never get the Steam version to register the Galactic Adventures expansion, and EA support were unable to register it on their end too.
Had no such trouble registering the keys from GOG.