Dang, the enemy ship being constructed out of modular pieces is really cool, I love it and it has so much room for expansion!
My main issue is that the background visuals clash too much with the gameplay, I couldnt tell what was killing me for a while because the bullets and bombs just blend in with the stars and stuff in the background.
Oh also I thought that I had to dodge the debris from the ships I destroyed... it doesn't hurt you, but maybe it's worth considering making it so that it does? It might fight the "junk" theme in the title x)
really clever gameplay hook, good job!