“Heroes of Might and Magic V: Tribes of the East”

O_o, either buy the Gold Edition (then you will play each campaign separately in its own version of the game), or install Tribes of the East, and add the All_Campaigns mod from here: /files/10154/>
The mod may have some glitches, I don't remember exactly, but overall it should be playable, and the changes in Tribes of the East are quite interesting.