Not many people, I don't think. You have to manually connect to an IP to play someone, which requires prior setting up. It's mostly used for solitaire battles, I believe, where a single person plays both decks. It's worth noting that Redshark is extremely minimalist as far as programming goes- you have to do everything yourself, from drawing cards, to manually discarding energies to retreat. It's a pain in the ass, to be frank. If you're looking for a TCG version of Shoddy Battle, you're out of luck.