Hey, I'm really happy you enjoyed the experience, and thank you for playing!
There is a lot more polishing that can be done and I'm taking in every piece of feedback I'm getting.
As for some monsters not joining the party, this is because only visible on-map monsters are befriendable, which I did mention, however I know it's confusing and not always clear (especially once you're in battle). I experimented with allowing every monster to be befriendable, but ran into some issues that I unfortunately didn't have the time to address so it didn't make it into the jam version.
Thank you for your feedback, every bit helps. :)