IMO instead of single license checkbox, you should be able to select by mutliple checkboxes the kind of CC license you want for your game.

So, by default it'd be CC0, but then you could check each part of CC license, so you can have any combination of by nc sa nd.

Here's the previous discussion on the topic of licenses: https://www.lexaloffle.com/bbs/?tid=2184

The biggest concern with offering multiple license options in the BBS is license incompatibility between components. By offering one explicit license in the BBS, you can safely use any component tagged with that license with any other component so-tagged. With multiple options, there's potential for confusion, incompatibility, and license violation.

Note that the feature only extends to the license icon added by the BBS. You are of course free to use any license you wish, and describe it in the comments of the code section or other front matter bound with however you're distributing the cart.