Is Heroes 3 a sport, like chess? How does the planning differ?

Well, I haven't played chess for about 20 years, so I'm not up to date on the current situation. To understand what we're talking about, describe an example of how you can make a move in chess that is forbidden to both opponents, and at the same time have a good chance of not being caught. (Violate the "fair play rule," if it exists there now).