Your aim is to accumulate more points in your home than the opponent. You do
this by redistributing the values of the pits, six of which you control, the
other six belonging to your opponent.

When it is your turn, you select a pit (one of your six, by pressing a key
from 1 to 6) whose value is to be redistributed. Its value will be set to 0,
and one of its points will be given to each of the pits that follows it in a
clockwise direction.

For example, if the pits were:

 1   2   3   4   5   6
[4] [3] [2] [1] [0] [4]
     ^
and you chose pit 2, pit 2 would now contain 0, and the three 'points' of
that pit would get transferred into the next three pits (each pit would gain
one point on top of what it already had), giving you:

 1   2   3   4   5   6
[4] [0] [3] [2] [1] [4]
         ^   ^   ^
Your aim is to get the points to land in your home area; the homes are
treated as normal pits as far as redistribution is concerned, so points
build up in the homes just like with normal pits. It's not that
straightforward, though, as you have to make careful decisions about which
pits to pick.

If your last point ends in your home, you get a bonus turn (but only one,
you won't get another one after the bonus turn).

Supposedly, you win by ultimately having more points in your home than your
opponent, but the game seems to choose when to end; perhaps it finishes when
you have 21 points (I think that I'll stop playing it for now).

That's most of the rules, although odd things do happen at various points,
so there are small quirks to the rules that I don't know about - try the
following sequence of moves, for example:

Player 1: pit 1
Player 2: pit 1
Player 1: pit 2
Player 2: pit 2
Player 1: pit 3
Player 2: pit 3

As each player picks pit 3, their one point in their home becomes 7. The
same happens if you pick pit 4 instead of 3 for the third turn. Why? No
idea. That is not the only time that your points shoot up.