- How to play Heroes 3 online.

I assume you're speaking from personal experience, which means I can trust you :) It's just that in two rather large gaming communities (Fortress, Red Alert), it's common to use the same version of Hamachi because users with older, un-upgraded versions will often disconnect from games created by users with the latest version. Maybe this isn't right, "the latest version wins," but in a way, this approach is more friendly...
Of course, the new version of Hamachi won't "block" games for users with older versions. But the opposite situation happens very often.