Is Sheikh Sa'd Al-Khatlan's statement that Nardashir is not the dice we know today correct? And if playing with dice (nard) is forbidden, does this prohibition apply to electronic games? And does the ruling differ if the shape of the dice is not cubic?

What appears evident is that "dice" (al-zahr) falls under the meaning of the prohibited "nard" (backgammon/dice game). Thus, any game that relies on the casting of dice falls into this category. Nard consists of colored pieces known as "ka'ab" (cubes or dice). The condemnation of nard is mentioned in the hadith (definition) with the wording: "Whoever plays with the ka'ab has disobeyed Allah and His Messenger." Ibn Mas'ud said: "Beware of these two marked cubes (ka'batayn) which are cast, for they are a form of gambling (maysir (definition))." And playing al-fustatayn as a form of gambling is like eating pork, while playing it without gambling is like dipping one's hand in pig's blood. Everything that relies on estimation is forbidden, and this rule broadly includes electronic dice (al-zahr).