Sargent Park GR8 Tech (Section 1 2016): Darshan Simple Scratch Game

Here is my first space invader game.  My base ship should move to the right and left using the arrow keys, a bullet should go up and down and blowup the alien.

pictures :http://www.clipartlord.com/wp-content/uploads/2015/12/explosion5.png
               https://nerdgeistdotcom.files.wordpress.com/2013/06/space_invader.jpg