[kemonocode]

You could make a case that making a cheat is copyright infringement as Blizzard did [0] so yes, it can be illegal.

[0] https://torrentfreak.com/blizzard-sues-overwatch-cheat-maker...

[JamesBarney]

It seems like blizzard is really stretching and the cases that already went to court they lost.

Is making an overlay a derivative work?