The term 'franchise' is mutated a bit in the game industry. They're new games that don't have anything to do with previous games (not a sequel, remake, prequel, etc.) so they're new franchises.
I have mostly seen this be named IPs (intellectual property), as in "studio X confirms it is working on a new IP".
I guess 'franchise' also works nowadays, as for any succesful game it will be profitable to make a sequel/spinoff/eventual remaster.
