Do those shadows drag your FPS to the ground on higher graphical settings, and even more so if someone made a mod that blurred them?
The great part is that this is all tricks, this isn't like the real shadows in blockland.
Shadows enabled eat up about 3 frames on my pc, reflections eat up about 6 due to transparency fuxxing.
The framerate will also massively improve once I batch the dungeon 
Edit: This stuff is all based on the same tricks they used back in the late 90s pc graphics, so it should work on almost all hardware.
These effects all look fantastic. Are you planning to save that effect for the ice mostly, or do you have like marble or metallic tiles planned?
The effect is controlled by the alpha on the dungeon floor tile, so it can vary depending on the level.