I think the solution would be to implement detection that silently reports offenders, gather up a big list of them, then publicly ban them all at once alongside any keys used by the same people. No way to forcefully stop these kinds of people, but the idea would be to scare people away from the idea of hacking the game. So you might be left with a few people who know how to forget the game up, but when they share their tricks around, people end up thinking "forget no I ain't touching that stuff" out of fear that they could be added to the next mass-ban list. If it's still a big problem, repeat the process with a different detection method. Otherwise just deal with the last few on a case-by-case basis.