In the 2000s they were among the go-to strategy games. The hot-seat mode probably helped. Of course, the publishers and devs saw little profit from all that following—unlike middle-aged dudes selling pirate CDs in mall stands.

HOMM 5 was developed by Nival, a major Russian dev and publisher at that time—though the 4 and 5 games weren't as famed, afaik.