GemStone

When the game begins, the text "Select Number of Players" will be visible. Press 2, 3, or 4 to begin the game. At any point during the game, press escape to return to the initial screen. Pressing escape while on the initial screen will exit the game.

Each turn of the game, the player places a point (left click) and if the point is accepted (white dot appears) the move can be accepted (right click).
There is a small radius around existing points where new points will be rejected. You cannot play outside of the white ring. All acceptable moves produce a Voronoi Cell about the point.
The players are scored by the area of their cells, which are themselves scaled by size of the region of which they are a part.
Regions are simply those cells of the same color which share an edge. The largest region has it's area multiplied by two, all smaller regions are scaled by the size of their region divided the size of the largest region. Formula is: score = cell area * (size of containing region / size of largest region).

The text in the upper left corner indicates whose turn it is (1-4) and the spinning colored ring in the background is the same color as the current player. The text also indicates how many turns that player has left. The text in the upper right corner indicates the current score for each player.

Upon game end, the upper left text will display the winning player and their score.