That's a really clever way to do it! Thanks for going over your process, it's a really interesting read. Shaders are amazing.
Yeah... you also get a lot of inspiration on http://shadertoy.com/
It's aweome what they do there. Some put the whole game logic into the shader...
My favourite game there is "Alien vs. Humans" https://www.shadertoy.com/view/XldGDN
For some reasons the sound doesnt work anymore. But, just open that music in background to it as the soundtrack (make sure to put it on repeat with right click on the video => REPEAT). Have fun shooting some alien ships!