RBounce
An animated board game for Windows
... for Round 2, and so on up to Round 15 (which no living mortal has yet reached). The goal for each round is to enclose and fill 75% of the board. Press F1 for a help message that describes the scoring formula and the effect of mouse clicks. When a game is running and the mouse pointer is within the playable area, a right-click switches between building a horizontal and vertical wall (the cursor shows which one); a left-click starts a wall building there, so long as no ball occupies that tile.