I always liked Defender, the old 8-bit Atari game, even when it kicked my tail. It was a fresh twist to be rescuing people from an alien invasion, rather than simply blasting away at said aliens.
Not so nice, maybe, for the poor captured humans, mutated into alien weapons to hurl at the player. This is the point of view I approached the game from when I saw some of the amazing artwork coming out of the I AM 8 BIT shows. A sort of "Invasion of the Body Snatchers"-meets-space-jellyfish creature helped me keep things fun as I explored the sad fate of the poor blips running around at the bottom of the screen.
Aside from the great source material, I also got the chance to play with a few recurring design elements. The wiggly borders from TakoButa-san show up, as do some of the things I was trying with Inoshishi.
Here's a look at an original screenshot to give an idea where I pulled some visual cues from.