The object of the game is to move stones around the board and score enough points to win the game.
Both players can see everything that is on the board. Each player must defend their positions while simultaneously exploiting weaknesses in the opponent's positions.
You need to select a pile on your side to move. To move the pile, just click on it and all the stones in that box will be picked up.
Circling counter-clockwise around the grid, one stone from the selected pile will be dropped in each of the boxes. This process will continue until all the stones have been placed back on the board.
You can score only if the box that contains the last stone is on the opposing side and has 2 or 3 stones in it. The stones are then picked up and are added to your total score. Here, the bottom player can score 3 points.
Now it is the top player's turn. Note that the rightmost stone is endangered. The top player faces a choice of whether to sacrifice the stone or to protect it.
Let's consider what could happen if the rightmost stone was moved.
As it turns out, the top player was able to make a 1 point gain on the opponent. But the move might have taken too many stones from the board to justify a 1 point gain.
Another move might have gained a similar amount of points with less point loss. This other choice might have been the simple alternative of eliminating the threat instead of running from it.
If this pile was selected, the top player could accomplish this goal.
This choice resulted in a two point gain with no losses. This move looks like a preferable choice, however as the game progresses you might end up pushing a bad position.
Once a player has scored, the game checks 1 pile clockwise around the board to see if it also has 2 or 3 stones. If this is true then those stones are picked up and it checks the next pile, clockwise. For example:
Here the bottom player was able to win 9 points out of one move and severely limit the opposition's resources.
That covers all the basics you need to know to play a game of Trist. As for strategy... that is for you to develop on your own.