Hello! I'm enjoying the demo a lot currently and I would like to report what seems like a bug to me: Placing any kind of objects (like coins, pots, enemies...) on walls that are created by placing lower ground results in overwriting the walls with regular floor tiles. You can delete the object and the floor tile stays in place, if you try to erase the floor tiles, walls are placed on them. At the same time those ground tiles still act as a wall though, so you cannot walk on them.
Hope this is helpful and thank you for your hard work! 😄