Oh, awesome! Yeah, this is a great example of something that I would have guessed would kind of be "over the line" being that it looks similar enough to be an issue. I'm glad it's not, though! But, either way, it's a perfect practical example of what I was wondering about, so thanks!

Unfortunately I think definitive answers are difficult to come by. No one cares that much about Transport Tycoon so no one is motivated to enforce anything. But if you made a clone of Call of Duty that had models as similar as OpenTTDs are to the original you might find yourself in hot water.