Overall, this is a fun board game demo with a lot of potential.
The story is currently a single background per chapter with a lot of different characters and dialogue. I'm not great at giving advice on story presentation, but I think this could be improved. As it is, I found myself mostly skimming the text as I clicked through, and it didn't add much to the game for me. I'd rather get back to the gameplay after just a few lines between battles. Maybe a small map where you choose where to go or who to fight next could help break things up.
I also think it would be really cool if the game pieces were eventually replaced with 3D figures of the monsters instead of checker pieces with letters on them. That would add a lot more personality to the board.
The Dark tiles don't seem to give Dark monsters the buff described in How to Play. Since Dark monsters also can't Fuse, this removes one of the main reasons to choose them.
Towards the end of the match, the opponent also stops summoning monsters even though they have plenty of mana. At the same time, I can't summon most of the cards in my hand despite having plenty of mana myself. There doesn't seem to be any explanation for why this happens.
Overall, I enjoyed it and I think there's a good game here. The core board game mechanics are fun, and I'd like to see how it develops.