Hell, man, you got off cheap. I talked to a Canadian guy who had lost $17,000 the week before. Over on Tripadvisor there are dozens of people with losses of $1000+. Still, 300 bucks down a rathole is just that. Theoretically the game is against the law, whatever that means in the DR. I talked to the guy running the Ocean World casino. He had been approached by several operators of this game, with promises of a 90+% return. He refused all.
I was in the casino in Playa Dorada playing poker when I saw a young couple getting sucked into that game. The script was being played out, and they stepped away to figure out how to get more cash and chase the big payout. I walked over to them and told them it was a scam. Of course, they didn't believe me, because who you gonna believe, a drunk old tourist, or Mr. Shiny with all the money? My friend the poker manager told me to be aware that the interested parties would surely take note of my intervention, and it was very easy to arrange an "accident" for me.
BTW, back to the OP's question, I didn't mention the Ocean World casino. When I went there two years ago, they would pay the taxi fare(from Puerto Plata) there and back if you went out there. It's the closest to a Vegas type casino, but small, like 3000 sq. ft. And they guy running the place is from my home town of Kansas City. Dead ringer for old David Crosby.