I see the 10.5GB number bandied about online, but that sounds like an exaggeration and I'm not sure where it originated. The full game digitally is listed as 11.8GB, though with the digital deluxe edition I've seen people say it occupies 12.2GB on their microSD or internal memory. 10.5GB would still be a lot of game left off the card in that case. While there are 1GB and 2GB game cards, I somehow doubt they cheaped out that much, that only two twelfths of the game are physically stored on the card. 3.5GB sounds a lot more believable to me, and since there are 1GB, 2GB, 4GB, 8GB, 16GB, and 32GB (and apparently 64GB but this is rarely done due to cost) cards, if it's on - say - an 8GB card, then 3.5GB would probably get it close enough to the 11.8GB full install for the vanilla version of the game's size to call it that. Granted, this is just speculation. It's entirely possible there is a 10+GB download required to have all of the game's content even with the physical edition. I haven't tried it firsthand. But if it's only 3.5GB as in your experience and people online are just inflating the numbers, that wouldn't surprise me either.