I have seen you have commented on your code but what I mean is that some of the complex logic is still missing the documentation or comment. Let's say for example, you have written a regex, which is quite big,

var regex = new Regex(@"[Uu][+-]?(?<hex>[0-9A-Fa-f]{2,})|say\W(?<say>.*)|type\W(?<type>.*)|(?<entity>&(?:[a-z\d]+|#\d+|#x[a-f\d]+);)|(?<time>(?<num>\d+(?:\.\d+)?)\W*(?<unit>s|ms))");

Now if I am a newbie in the project I will not understand what exactly this Regex does, so explaining it would be highly appreciated. Thus we say that commenting and explaining the complex logic is necessary for open source project because that helps the people who will be using your code.