Not really - "Everything is open-source if you know Assembly" - Look at Ghidra for example.
If code isn't obfuscated you can do an analysis what kinda stuff closed source software does. In C# (so if his game is written in Unity) you can even get very close to the original source code (IL code reversed back to C#).
That's why I mentioned anti-virus isn't going to be happy about it. You can easily google examples: examples[1]example[2]example[3] - that obfuscating is a red flag to a lot of anti-virus