What would you change in Heroes of Might and Magic IV?

I would improve the AI, which mindlessly tanks with its units and makes the same tactical mistakes on the global map. Overall, the AI is capable and keeps things interesting, but it is quite predictable and linear. At higher difficulties and/or in the late game, it miscalculates its strength and, as a result, foolishly dies against neutrals or completely loses its army in a major battle. The concept of a "major battle" is probably simply not present in its databases.

The endless cycle of capturing and recapturing buildings. Perhaps I'll suggest a controversial idea, but capturing on the map should be done with a delay or require spending part of the current day. Or even divide all points of interest by value, so that some are captured on the fly, as it is now, and others, say, take an entire turn. Plus, freeze the recapture for 2-3 turns.

The same applies to capturing empty cities. You enter, place a flag, and leave – it's fun, but it needs to be balanced. Especially considering the city's development level.