Group: a group is an entire group of connected stones on the board of the same color. A single stone (unconnected to others of the same color) is also a group.
Overgrown: a group is overgrown when it has more than 5 stones in it.
Smothered: a group is smothered when there are no empty spaces adjacent to any of its stones.
- Each player owns 2 stone colors. To start, Player 1 places one stone of either of her colors on any empty space.
- From then on, starting with Player 2, the players take turns. On your turn, you must place 1 or 2 stones on any empty spaces. If you place 2 stones, they must be different colors.
- After you place your stone(s), capture all smothered enemy groups, and then capture all overgrown enemy groups.
- The first player to have captured X enemy stones wins.
Because your opponent can only place 2 stones each turn, she can't smother any group touching at least 3 empty spaces. So ensure your most important groups always touch least three empty spaces.
It's possible to create situations where a group has 3 or more empty spaces your opponent can't ever fill. This makes the group un-smotherable, a big advantage. The methods for achieving this are complicated and still poorly understood, but be on the lookout for opportunities to do this.
The board consists of concentric rings of hexagons. The the second-outermost ring is important, because groups with lots of stones on that ring are hard to capture without losing a lot of stones in the process. Therefore, in the game's opening phase, place most of your stones on that ring.
When you make a size-5 group, it can no longer evolve, which reduces your flexibility. Don't make a size-5 group unless what you gain from it is more valuable than the lost flexibility.
If your opponent has two size-5 groups of different colors that both touch the same empty space, she can't place a stone there without overgrowing and losing one of her groups. Therefore, if one of your groups is adjacent to that same space, your opponent can't smother it without overgrowing, giving you an advantage. Such empty spaces are called strong liberties. Try to force your opponent to make strong liberties for you, and avoid making strong liberties for them.