Beat it! Had a fantastic time playing. Really enjoyed a lot of the design decisions. I like how combat automatically happens as you run by enemies and you don't have to stop in your tracks for every battle like some other monster collection games.
I collected 25 / 27 monsters. Can't for the life of me find out where the last 2 are. Looking at the trailer, I can see what they are, but can't find anywhere in the game I haven't explored yet. Since one of them appears to be connected to one of your previous games, I wonder if I have to do some meta messing with the files or something to get it.
There were quite a few collision problems with the game where I would get stuck in places and have to exit to the main menu to get out of the soft lock. You can clip into the house in the surface by walking through the pipes on the left side of it, you can clip into the no-collision door that drops you into the pit of enemies by moving along the side, and you can clip into pretty much every prop in the game (although those don't have collision on the inside, so you can walk right out).
Overall, another fantastic game. Well done!
EDIT: I was able to get the last 2 monsters by editing the save file, but I don't think that's the intended way of doing it. Not sure if there's an in-game way of collecting the last 2 monsters. Would love to hear if anyone has found a way.