So what's Cathedral? Cathedral is a great game that I originally bought because I thought it would look good as a decoration of some sort at home, but then I decided to take it to work in case I would get to play it. I've played a little more than twenty times now, and it's excellent. There's a lot of strategy and depth and tension in each game, and it emphasizes learning how to beat your particular opponent instead of just tricks and general skill. So, each game evolves, with each player learning a little more about the other and trying out new things to win. It plays quickly enough that you can play often, and like chess, it's something that lends itself to "take a turn, come back later, take another turn," and games that span multiple days.
It's really caught on with the interns. My board now makes its way around the building with different people borrowing it. I don't even actually know where it is right now.
The game is simple: don't be the one who can't place all of his pieces. Each player takes turns placing their Tetris-esque pieces (buildings) on the board, anywhere they want. The only catch is that if a player completely walls in an area with their buildings and that area is empty or contains exactly one piece that isn't theirs, they claim that area: from now on, only they may place pieces in that area, and if there was already a piece there, it's returned to its owner. It sounds boring, but it's quite exciting in practice. You have to balance your own play style with what you know of your opponent, guess how likely they are to spot the particularly excellent move that you want to make next turn, and make sure that you don't use up your most useful pieces all at the beginning or save up the hard-to-fit ones until the end. It's basically everything I like about chess without the annoying parts. It's much easier to survey your position and your opponent's position on the board, so it plays quickly even when there's a long delay between turns (like if you're just doing a couple turns a day). There's still the element of understanding how your opponent plays and using that against him or her. And, unlike chess, it's very easy to explain to others, and you can play very well right from the start, without studying the game.
It's been one of the best blind purchases I've made. I figured that even if the game were stupid, the pieces still look cool, and it would look nice sitting out. Now everyone's borrowing it.