Heroes 5.5 WarGame Edition - Tactical Edition.

As for the thresholds, the original 0-3-6-9-12-15 are already too slow, so turning them into 0-30 would make them even slower. By day 7-8 of the game, we should be able to access any top-tier technology, just like in Heroes 3, otherwise, goodbye to the game's pace.

Well, the pace won't disappear – building a structure immediately adds more than one level to the city; it adds two, which means the city level grows faster. The thing is, not every building increases the city level by 2; only dwellings do, which means the coefficient should be less than 2 – I don't know what it should be yet, but I'm guessing it should be 1.5.