HoMM3 HD is a mod (add-on) for the game Heroes of Might and Magic 3.

If enough people express their support for counting down after a turn is accepted, I might implement it with a chess timer. However, the timer is meant to shorten the game time, but what kind of reduction can be achieved if we can take turns indefinitely? Also, all the risks associated with delaying a turn can be taken into account when setting the time limit. But this is just my theorizing; as you know, I don't play online myself.