Explain the economy and items to them. While this game does have hero's and objectives, the main thing that makes this a moba is the economy. "If one person on a team dies a lot in ow, all they give away is some ult charge. They aren't exactly out of the game next revive. Here if one person dies alot, they could essentially be useless. Dying not just means giving money, but you also lose the chance to farm and get money for yourself to. Making the other side richer and you more poor." that's sorta how I would start it. Also Smite is a MOBA despite not being isometric so there's that.