There are some hobbies that should not be disclosed on a resume or in an interview. These are the sorts of things for which some employers would immediately stop considering you for a job. Thus, revealing such a hobby would not be worth putting the activity on your resume.
However, as others have said, gaming isn't necessarily an embarrassing hobby and isn't likely to get you immediately removed from consideration for a job. A few people may find gaming to be a hobby for immature people, but others won't - some may even be surprised if you are a software developer and aren't into gaming! Overall, I don't think there is a great risk from revealing this about yourself.
My problem now is that putting this on a resume would obviously point
out that i am into gaming, which might be seen as immature.
Not to be rude, but why? Is there really no way to put this on your resume without mentioning the gaming? Couldn't you have a "Personal projects" section with a bullet point something like:
- Developed program to analyze user actions and use that information to automatically navigate the software being used
(Or something better describing what you wrote.) Once you're in the interview, if you're asked about this, you can describe what you wrote, and only briefly mention that it was for a game. As you said yourself, this was to prove a point - if that point came as a result of a conversation with a friend or it was just your own curiosity, you can say that was the motivation and move onto describing your project.
More important i have broken ToS in the past ...
Ah, this is where things get trickier. Some places won't have a problem with this, but others will have major problems with it, and it is unlikely you will know which you're dealing with when you are in the interview. If it is impossible to avoid disclosing this, then you may indeed want to avoid mentioning it altogether. However, if it's not clearly a violation, and/or you can discuss your actions without getting into the ToS issues, then it may be worth the risk. If the ToS does come up, you may be able to say that you're not a lawyer and didn't realize this would be a violation, since you just did the project for your own edification; the first and last parts of this certainly seem to be true, it's the middle part which might be fuzzy, but I doubt you'd be asked about it, and if you are, I expect you would not face follow up questions to an answer like this.