Vitya, no, there is no 'bare king' rule in HyperModern Shatranj. The operative rule is:
'Victory is by checkmating the opponent's king. Any other result is a draw.'
It is true that every other shatranj variant I designed has a bare king rule. However, by this point, the game is close enough to modern chess that such a rule was not considered. I don't recall Roberto, Christine, or I even mentioning it during our various discussions.