A new spatial reasoning game that I stumbled upon at my FLGS (Friendly Local Game Store) was Abalone.
Abalone is played on a hexagonal board in which the players each control one color group of marbles (black or white). When moving marbles, the following are all legal: moving 1-3 marbles laterally, or using 1-3 of your marbles to "push" your opponent's marbles. If you push marbles, you must have more marbles in your line than your opponent, and you can only push up to two of your opponent's marbles (in a single move). Players take turns making their moves and attempting to push their opponent's marbles off the board until one player has knocked 6 of his opponents marbles off.
Now for the pros and cons section. (Good luck, I always have to make this up on spatial reasoning. I try to get more and more creative so they don't all sound the same. Otherwise, you would constantly be reading "I have no idea what I'm doing in spatial reasoning games." Of course, I think that that is why I like them. Anyway...) The strategy in Abalone seems fairly deep. There are enough marbles and enough empty spaces that there are many moves and counter moves. Just when you think that you have one of your opponent's marbles pinned down, he will make a lateral move that will cause you to be horribly out of position. You must also occasionally balance whether it is more important to play offense or defense; I often encountered situations in which I could knock off one of my opponent's marbles, but at the cost of one (or more) of my own.
The combination of pushing and lateral movements works very well in this game, and a large reason for this is that it is built on a hex map. If the game were built on a square, I do not believe this would work at all. One of the best strategies that I have found so far is to cut off my opponent right after he has pushed my marbles. For example, if he has used 3 marbles to push 2 of mine, I find it advantageous to be able to then push one of his 3 marbles from a different angle so that he no longer has the power to push my marbles.
Another strategy that I have found in the game is to get my marbles intermixed in a large group belonging to my opponent (or "arch-nemesis" if you prefer). If one of my marbles is in the midst of his, it can often cause him to be unable to get 3 marbles in a row, as he is not allowed to push my marble into one of his own marbles. This can cause my rival to get out of position while I try to counter him from a different angle.
Now for the obligatory spatial reasoning paragraph. I really like spatial reasoning games (that I consider "good" spatial reasoning games), because I never feel like I'm good at them. They seem to challenge my mind in an entirely new way than any other game that I have played. I realize that these games aren't for everybody, and that's ok. In fact, I was not really a fan of the genre until the last few months, and since then I have been trying as many of them as I can. In trying all of these, I find some occasionally that jump out to me as favorites almost immediately. Abalone is one of those new favorites.
Now for the cons. First, I haven't really decided if I think that people will get together specifically to play Abalone. With that said, I am sure that people who truly enjoy spatial reasoning games do get together to play them, but I suppose that I should say I cannot see myself meeting with someone for the sole reason of playing Abalone. However, I do think that I would get together with someone to play a handful of games, one of which would be Abalone.
The next con that my wife pointed out while we were playing is that it can be potentially difficult to visualize the game. Since the game is played with black and white marbles on a black background, it can be difficult because of the lack of contrast between the black marbles and the black playing area. This was not something that I had trouble with, but it is something that she pointed out as a problem for her.
Overall, I give Abalone an 8.5/10. It has jumped to the top of my spatial reasoning list right alongside of Gipf, Yinsh and Dvonn, and I look forward to continuing to play this game.