A lot of poker game tournaments have been announced on this board over time, and am I kind of wondering what makes poker games so inclined to the tournament and we don't see such competitions being announced for other games?
There are competitions for other games here that are being held by different casinos. You can find them in Games and Round board. Some are free to enter (usually when the game is about prediction).
But if you're referring to games that aren't initiated by casinos except poker tournaments, it is because no one initiated it.
Aside from that, competitions can only be host the the casinos if there’s a demand for that games because if none, that may become a useless competition because very few gamblers will participate or none at all. Poker is a game of strategy, and having a competition with this game will be more entertaining, I watched some tournament before and I can say that the interest for poker game is very high, also its fun to watch Poker where you can also learn from the strategy of the gamblers.