We did a reverse shoot-em-up too, but focused on the boss fight/bullet hell aspect. I expected it would be difficult to balance something like your game, where you're summoning armies, but you did a pretty good job of it! I survived with just 4 health to spare. :)
There's probably a setting in Unity that lets you scale pixel art cleanly - it's a bit of a shame that the boss ship was a big blur.
Nice work! Well done executing on the concept.