and the prize pool is 1,000 FS for 25 winners, I still don't know what is FS?.
mrtornado is right. FS stands for
free spins. If you scroll down on the FAQ page you shared you will find more information about the
slot of the week competition and how to participate in it. Here is the relevant part to your question:
score points and try to get into the top 25 to… well, get free spins to this slot
Don't know about you guys, but I find the 50x wagering requirement a bit too much!
50x is a bit on the high side. Every casino has its own conditions to play a bonus or money, but 50x is almost impossible. Usually it is between 20 and 30. Also quite a challenge, but sometimes it works and then free money is always a nice bonus. Maybe the site can adjust this to make it more attractive to players. The cashback is also a nice promotion, but implies that it is only for losing players. What if players win? Is there something of an action or promotion?