Yeah they have probably the best free roll structure. The prize is small but only 6 players can participate so it suits both players as well as casino. I am able to win it a couple of times and yes, the cashouts are instant.
The only add on would be to raise the prize pool to $10 with at least two places paid.
I think the 5$ reward and the 50BITS that is about 3.75$ per tournament is already reasonable, considering that the tournament runs every 2 hours. If we want to see this tournament to continue in the long run, that's probably the best way which is to maintain the reward as it is, and of course it would also be good if we see more people actively playing cash games.
Maybe what they could add is to have more reward in chat rain or at least lower the minimum amount required to play in their games. I received chat rain rewards a few times already, but this amount is too low to meet the minimum amount required to play. Unlike in the early days when they start to operate, I saw someone receive 3$ in chat rain.
Another thing to add is the emoji. I can use emoji if I'm using my mobile phone while playing, but if I'm using my computer, there's no option to use emoji in the chats. Adding this would be good to have more engagement.
