Got around to playing with the Arcade modes. It was fun, but also needs some work still. AI for example, seems to get stuck while pathing, spawn in the floor/ceiling, and get extreme tunnel vision for the player over AI enemies that may be actively harming them as they make a beeline for you. Performance was mostly fine, but a few levels/challenges had a good amount of stuttering when first loading in that persisted for around 10ish seconds. Overall, it feels as rough as you would expect from an early access game (though not unplayable like a lot of those can be). They have the foundation here, and they just need to polish/improve on it while filling out the missing content. I hope it goes well for them and doesn't take another decade to accomplish.
I haven't tried the campaign or online multiplayer yet. I was waiting for a friend to try it co-op. I saw there were quite a few online games going when I checked last night so I might try that too.