Very nice experience. Overall I will give it a 7 to 7.5 out of 10.
Let's talk about the good stuff first. This game is being carried HARD by its storytelling. Not just the story - I would say the story itself is just good at best - but the atmosphere and the delivery are just awesome.
Major factors on why it is awesome: Crispy voice acting, beautiful background musics, and cool CGs (yep, you can tell I'm a sucker for visual novels). The story text itself could make use of some refinement here and there, but I'd say it's still nice.
Now let's talk about the stuff that needs to be taken care of: the gameplay. To be fair, the game itself is obviously far from polished, hence the janky gameplay. But, to me at least, the gameplay did no justice to the fantastic storytelling.
Bugs here and there, monster AI not working as intended (based on my expectation as a player, that is), weird checkpoint/spawn location, lacking features (such as running), and...... Well generally, more work needs to be done to make the gameplay proper.
I'm hoping to see more of Cain's story in the future.