I agree on the critique on the boulder animation, the light-source shouldn't change... but if it's a programmer limitation, whatever then. The tiles all look quite good. I specially like the walls, the pit with the metal web, the carpet and the key on the top-right (looks the best), and the boulder looks ok too if not animated
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The scorpion looks too flat, even with the ground shadow: try darkening that shadow and/or adding more shades, or playing with its contrast. That dwarf-face thing (in the top middle), doesn't quite fit in the "dungeon" style, it's too cartoony. And is that a milk bottle? In a dungeon... ok
Good luck with the remake!