Op is looking for a casino that has no lots of games combine, I think the website you've mentioned have variety of games they are offering.
It could be very difficult to find a single game casino site only but one slot of game maybe with another features. Nowadays Gambling site is basically focused on multiple slots due to its competition around so he could choose any above listed or should go bet with fiat instead. For me names and branding really matters (Ratings and reputations) and i can see the rate at which those casino's site already gained from most of our reputable trusted users here.
I know it will be a hard thing to fine a single game base casino most especially slot base, but some of the few i have seen have great features and loads of benefits most especially for players with high rank accounts. So am thinking if one can find new casinos that offer such services.
Have you just changed your preferences? Previously you are looking for slot only casino and now you are talking about benefits for high rank accounts which is supposed to be VIP program. Most casinos has this where you get benefits based on your wagering activity, the more you wager the more rewards you are going to grab. And why should be new casinos while reputable casinos are there for you to give better experience.