"Intellectual Property" is a misleading notion because it is an umbrella term for all kinds of legislation, none of which are actual property in the material sense. Copyright, licenses, trademarks, patents, they all work in completely different ways so it is very confusing to think about them as one and the same thing ("IP") which you can "infringe".
Code and game assets are copyrighted by default, because authors/artists get the copyright whether they want it or not. Copyright only talks about (verbatim) copies, not things like remakes, parodies, covers, etc.
Patents can be used to protect against "copying the abstract idea, not the concrete implementation". But while software patents are (sadly) allowed, you still can't patent a plot or a game concept afaik. It would be surprising to me if there are specific patents involved here.
Trademarks are probably not relevant here.