Changes made from andy’s original ping app:

1. Added two additional bats (top and bottom)
2. Added basic collision detection between bats and the walls (so they don’t fly offscreen)
3. Made the two top bats move back and forth by themselves
4. Added collision detection between the bats so they can’t occupy the same space
5. Top and bottom Bats increase and decrease ball velocity respectively
6. Added an automatic reset to the game
7. Made the starting bat random (can be both left and right)