Sources simple game "Shoot down the plane" C#

The source code of the game "Shoot down the plain." The game is the random appearance of enemy aircraft that move horizontally. The player´s task is to control the gun, which can be moved using the left and right arrow keys, to shoot down the enemy plane, firing a projectile by pressing the space bar. For each aircraft brought down the player is awarded a ball. If an enemy plane crosses the screen, the player loses and the game ends.