There is no shortage of go reviews. I'm writing this one because there isn't yet a completely one-sided lovefest for this great game, and (as a completely biased fanboy) I think there should be one.
I'm not going to cover the rules. They can be given in a few short sentences, but that isn't what I love about this game. All you really need to know is that go is a perfect information, luckless, abstract, 2 player game.
Before, During, and After a Game
When I know I'm going to be playing a serious game of go, I get excited and nervous together. I know it'll be a blast, but the nervousness is: Will I play well? Will I discover clever insights as we play? Or will I overlook something stupid and play badly?
During the game all my concentration is focused on the board. I am thinking as hard as I ever do, and all about the abstract situations that are arising. After a long, hard game, the stress will be so great that my hands will be shaking and I can barely stand up.
For days after, I will be running over the game in my head. Thinking about the positions that happened. Trying to work out which moves could have been better, and why. Trying to figure out what my opponent might have known that I didn't.
Something New Every Game
In almost every single game of go, you will discover something new. Although go is theoretically fully calculable, the calculations are so fantastically beyond what any human can manage that pattern recognition, intuition, and experience are just as important as raw calculating. This experience helps in both tactics and strategy. And this need for experience means that you should be taking away something new that you didn't know before from each game. You're never "done" studying go.
Tactics Too Complex to Fully Analyze
Tactically, when you are trying to read out what will happen in the next few moves, you can't consider all the possibilities. There are too many. You have to quickly decide which moves are likely to be important, then see what they lead to. Finding the unexpected move that your opponent overlooked and that thwarts his plans is a great boost to your ego. 511
When you overlook a move that your opponent sees you need to remember it, so that next time you won't be caught the same way! When you enter into a complex struggle, and you know that both you and your opponent are at risk of making mistakes, you must fight desperately to make sure that you don't make a move that gives your opponent a crucial advantage in the rest of the game.
Deep Strategy
Strategically, experience and intuition are even more important than in tactics. During play, patterns form on the board, and nearby patterns (and sometimes even distant patterns) will interact, forming larger and larger constellations of meaning. Sometimes the stones are arranged to score points. Sometimes they threaten the safety of enemy stones in the area. Sometimes they invade into enemy territory, taking away area that would otherwise be points for your opponent. Sometimes they are vague and flexible, stones scattered through an area that can be turned to multiple different purposes as the need arises. Sometimes your stones are arranged badly, and do nothing but give your opponent easy targets to attack. All these considerations may take over a hundred moves to become fully clear. Were you able to find the moves that made the best patterns and shapes for the situations?
A Style For Every Player
Every player has a different style. If I was shown a record of a game between two frequent opponents of mine, I would have a good chance of knowing which player was which color on the board. Partly this is because of the strengths - is this player good at fighting? Does he or she make efficient structures early in the game? Do they tend to make surprising moves that work out well? Or do they fall apart when their groups face a fierce attack?
Another difference is in how a player values different aspects of the game. Some work towards solid points, "cash in the bank" as its called, from the very beginning. Some work hard to make sure all their pieces are safe; others don't worry if they lose some pieces, knowing that they'll make up the difference elsewhere.
This variation from one player to another means that each time you play somebody new, you're going to have a game different from the ones before. They'll show you new board situations that you need to examine. And each game you play with them after will give you a better and better picture of how they play and what they're thinking about as you play them.
A Tiny Bit of Balance
Now I'll tone down the fanboy-ism a bit. I realize that the game isn't for everybody. Even if you like themeless abstracts, even if you enjoy 2 player games, you still need to be ready for the brutal learning curve. 237