I had the same idea as an "over the weekend" project. I had the sprites moving (with each invader's "arms" animated while the grid moved) and could control the player. Clearly the "over the weekend" was too ambitious, and I stopped before ever trying to add fire/bullets/collision/etc. So I essentially got no where, but effectively killed the weekend while spending $0 while avoided doing other things that would have definitely cost >$0.

So congrats on sticking to it to complete yours