The game is great and will be super cool if add COOP.
Also i want to help you to improve that cool game, where do i write here or on Stam ?
The Steam forums are preferred for feedback and discussion. It's a bit easier to discuss different topics with separated threads.
I would love to do co-op but for now it isn't a planned feature. Depending on how well Early Access goes I may look into what it would take to add co-op during Early Access or after release. Sorry I know it is a feature people really want.