add liquifying to each type of material, for example diamond plate and metal may be slow and hard to swim in while othe materials like wood just can't be liquidifyed, so you can have molten things instead of putting a decal block over terrain water
This'd be kinda cool, why not.
You live in a BOX Your life IS A BOX you will never get out of the BOX so long as you refuse to accept the existence of anything BUT THE BOX.