RBounce
An animated board game for Windows
...Wall ends grow till they reach the game boundary, or another wall, or meet a ball. If a ball strikes an active end, the wall stops growing at that end; if a ball strikes the side of an actively growing wall, both ends stop and the player loses a "life". Each round begins with as many lives as balls: 2 for Round 1, 3 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.