I think (hopefully what i describe below has not infected unreal made games) that you misunderstood idea of crypto mining in unreal.
There are several (whole class) of trojans/backdoors that install mining software and your PC is mining for somebody else, and you do not even know about it.
So “mining in unreal” most probably is:
- you buy asset swap cheap game (or get free game)
- it has embeded mining software, or just downloads it later, and installs (like backdoors do)
- then your PC is turned into mining station for somebody else
- when you uninstall game, it either removes mining software (well that is grey area game), or it does not (and that game is plain malware). Btw same goes for web browsers and other shareware stuff, even some big companies do it (ie. they do not uninstall miner nor they tell user about it) which imo turns their software into malware regardless how big that company is.