You can install games on your HDD, keep in mind it will be formatted in a WiiU specific format and you won't be able to use it for anything else (not even Wii games as those use a Fat32 drive, you can use UStealth to be able to use 2 drives on your WiiU, one for WiiU and one for vWii). You can install games on the SDCard with Loadiine (WiiU) or WiiFlow (vWii). If you talk about transfering your games to your HDD without using your SDCard, you can't, but you can FTP to your SDCard (pretty slow as said above). Keep in mind that SDCard's prices are very low now (you can find 128GB sdcards for around 20 €), so i would recommend you to get a bigger one. EDIT: It is technically possible to use Mocha-Fat32 Support to use a secondary HDD as a temporary SDCard ... I haven't tried it and i wouldn't still recommend it as sdcards are cheap now.