Consider CC0 or MIT for fallback license.

[Poikilos]

I have read the announcement regarding posting the code on GitHub and understand your intention is to make the game and code widely available. The CC0 protects you better (has disclaimers designed by the Creative Commons legal team) and is more internationally clear than what the U.S. calls public domain. If it is labeled that way in other countries, and someone makes an improved version, their government may end up owning that version. Consider adding CC0 to the repo as the fallback license, as opposed to stating "public domain" in the readme. You may even want to make the fallback license the MIT license, if you're not forfeiting copyright, but by declaring it public domain you already have I think, so CC0 may work better.

[miskatonicstudio]

Sorry for not answering, GitHub didn't send any notifications about issues/PRs.

Using an explicit license seems like a very good idea, thank you for this suggestion. I thought that "public domain" is also a legally binding thing, but apparently that is not the case. I'll try to upload the CC0 license sometime soon, after making sure that it will not affect any resources that do not belong to Miskatonic Studio.