Just noticed Abyss has released a new game for Amiga called Tiny Invaders. Looks like it is only 18 KB in size!
"This is a tiny Space Invaders clone, done for fun some years ago but never released until now. Enjoy hundreds of parallax stars, more then 60 animated objects on screen and over 200 hundred colors. And all that at blistering 50fps. The future is now!" (source: readme-file)