Great fun this past week and I learned an enormous amount.   Thank you to everyone for their help.

Many of the submissions are fantastic.

I'm off to my son's soccer game and then taking the family to the beach.

In addition to programming, I also learned about copyrights and royalty-free licensing for both images and music.  I've tried to be compliant with all copyrights and licenses that I could learn about.

I started to experiment with mixer channels for the first time so that the sound doesn't get cut off during a clip that repeats.  For example, the game can now play multiple gunshots and explosions at the same time.

I never got smooth scaling to work on the graphics.  I created different models that used surface scaling, but I never got it to work properly.  I definitely want to use Sprites groups the next time.

I also created a different version using USEREVENT custom timers using pygame.time.set_timer().  This version doesn't have custom timers.  I still need more practice with that.  Maybe I will be able to use the pygame Clock more effectively for the next challenge.

This was my first experience trying out Inkscape.  I had a tough time using it.  GIMP remains challenging.

Right now, everything is in one single file.  I hope to break it up into different libraries next time.