On The Edge is an abstract block-stacking game for two players:
From the Rules:
Be the first person to stack your cubes on their edge making sure not cover any white square in the center of each cube.

Play of the game:
Each player takes 8 of the same coloured cubes. Each cube has a weight on one side, so that when stacking players will need to put the side with the weight on the cube below it. To start, take any cube from your pile and place it on a flat surface in front of you. Take another cube and stack it on the edge of your first cube. Be sure not to stack the cube on the white square in the centre. Continue stacking until you have stacked all 8 of your cubes. If your cubes should fall, continue stacking.

There are two alternate ways to play: a race to stack your cubes or take turns and stack on a shared stack. First to cause the stack to fall, loses the round. Play for five rounds.