Don’t trust code comments over 30 hours old. Inevitably the comment isn’t updated after code changes, resulting in confusion and bugs. In fact, I wish every IDE (Xcode, Eclipse, etc.) had a feature/plugin that would redact comments whenever code is changed, in order to force comment revision.
Here is how it would work. Given some commented code from a game:
/* Add a fixed bonus */ score += 100;
Any change to the code would immediately redact the associated comment with X’s:
/* XXX X XXXXX XXXXX */ score += time_left * 2;
Alternatively, it could reduce the comment to an Mad-Libs style fill-in-the-blank exercise:
/* _verb_ a _adjective_ _noun_ */ score += time_left * 2;
Either way, the coder would be forced to rewrite the comment to match the new code. This would encourage short comments, or better yet, no comments.