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.