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

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.