I was able to play this game on another site in demo mode and it is nice
You should try the 5 scatters bonus round. That is probably the most expensive bonus buy ever, even with the base bet of $0.2 you need $400 to purchase it. Thats 2000x and you need to hit 2000x just to breakeven from that but every spin is literally profit however the winning factor is to land one of the premium symbol onto the reels
I haven't buyed any feature yet on slots and I don't think I will ever do it. I don't want to risk a lot of money with a couple of spins. I know it can pay out really wel, but a little bit too risky for me.
Watched some videos on youtube about the 5 scatters bonus round and most of them got their money back or had even a nice profit. Key seems to be that your wilds need to be in a good position and that you need multipliers on your wilds to score a big win.