And Heroes 3 just happened to be in the right place at the right time, and it was already a well-established brand; around the same time, Age of Wonders came out, a unique game of its kind, with amazing ideas and much better than Heroes! But it didn't succeed because all fans of turn-based strategy games were busy playing Heroes 3...
In general, I would rank my priorities (in descending order) in the Heroes series like this: 5, 2, 3, 1.
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But I completely agree that Heroes 3 is an evolution of Heroes 2 and 1.