We have just launched a Free DLC package titled Galagan's Island: Metagalactic Monstrosities, originally created for the Ludum Dare 33 Game Jam.
In this DLC you control the bosses from Reprymian Rising, trying to destroy the hero.
This DLC uses separate application file to launch. After downloading the DLC, when you hit "Play" in your Steam Library you will get a popup asking whether to launch Reprymian Rising or Metagalactic Monstrosities.
As we move forward, we will be continuing to update and polish this DLC alongside our work on Reprymian Rising.