Poker.co = amazing
Slots.co = Amazing
PokerSlots.com = still good
PokerSlots.co = A little too niche that I don't see any company actually buying. While gambling is popular .. there are relatively few players in the industry given the massive amount of income. As such the actual need for specific niche names isn't bad .. but not high enough that they would go for a niche domain in a .co .. UNLESS it had traffic .. but that's a completely different question.