They are still working on new weapons, enemies, and obviously levels. As of this post they plan to release the game in 2020. I do not know if they mean Early Access or the Finished Product. In case you hadn't heard, the game will ship with a level editor the day it releases. Prodeus will also have Workshop support, too.

Andrew Hulshult is doing the soundtrack and he posted a few videos on YouTube that let you get a feel for the songs (they're pretty good).

Check out the Kickstarter and Twitter pages of Prodeus for more updates. Thats what I do at least. Prodeus also has a Discord server you can join. Last, be sure to subscribe to their YouTube channel as well.

I hope this helps.