There is an Android backgammon program (several million downloads, most of them free and sponsored by ads, the rest of them paid for) that I have long suspected is cheating.

I have finally, after a lot of hard work and my own programming skills, managed to reverse engineer the APK (even though the developer has tried to conceal his dodgy dealing behind ProGuard).

Is it illegal for me to publish the bits of code that do the cheating?

I'm mindful of the whole "intellectual property" thing......but if something is dodgy, it needs exposing surely?

  • 1
    Is it cheating by breaking the rules of the game or by cheating on the random number generation? Perhaps you discovered the specifics of the cheating by reverse engineering, however, once that you know the specific way that it is cheating, it should be possible for you to demonstrate the cheating to someone else without showing the source code.
    – Brandin
    Oct 4, 2022 at 8:09
  • 1
    Also "cheating" is a bit of a strong word. I would simply say that the game is unfair, or that it's not following the rules of backgammon, or that it's not using fair dice rolls, or so on. Those are all factual statements and you can demonstrate them.
    – Brandin
    Oct 4, 2022 at 8:11
  • How much code are we talking? You might be able to publish some short extracts as "fair dealing", particularly if you have discovered a genuine case of fraud/deception (or other danger such as security flaws). Fair dealing allows publishing limited extracts for criticism, review, or news reporting, any of which may be argued to be the case here. But you certainly can't publish the whole thing, and you should be mindful of defamation/libel. This is why media organisations have lawyers.
    – Stuart F
    Oct 4, 2022 at 14:34
  • What exactly do you mean by "cheating"?
    – gnasher729
    Feb 1, 2023 at 12:39
  • Instead of using the randomly generated dice it substitutes its own to gain a material advantage. Feb 9, 2023 at 16:51

2 Answers 2


You could experimentally test the legality of this action. The law does not generally condone vigilante action, and copying and distributing program source code is, on the face of it, illegal copyright infringement. However, in the US you can try the "fair use" defense. That means you would have to go to court, but your lawyer would advance an argument that this is allowed copying. The main argument would be based on "limited extent of copying" (if you only publish a fraction of the code), and the "comment" purpose (essentially, expression a political position by showing "This is what he did").


Regardless if the app is cheating or not, you should not disclose any close sourced applications source code. Android may be open source but the apps on it are not. You could be wrong and be open to both copyright infringement and defamation of the application. I would report it to the Google Play store rather than trying to vigilante programmer. As you are from the UK, you might want to report it to the gambling commission if you get no success with Google.

I am not sure how useful the US fair use explanation you received already was, however fair use doesn't stop things going to court in UK I don't think, but I believe it can be used as a defence in a court in some situations but it isn't always fair and not something to rely on. When you say publish, you have not mentioned published where, but if publishing publicly then I don't think fair use covers that. If you just share what you found with i.e.. the gambling commission or google privately, then it is more likely fair use can be used in a court if they took action against you.

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