If you know what quick sand is, then you know its basically sand wish a spring under it. so I thought, why not have sand you fall through a little slower than water, cause of the sand, but still fall through. It drowns you while in it, and you need to work hard to get out. Or it could constantly drain health instead of drown you. it should give wet sand when picked up, and when placed it will only be that quick sand substance for a while. hot areas (like desserts) will drain it REALLY fast, while cold areas (like tundras) will make it Ice Sand (looks like sand, but has the properties of ice) but all quick sand dries out with out water coming up from underneath it (unless its a cold area, as stated). the way i mean by water coming up from under neath is like selected geyser or spring blocks directly below them. what do you think?
Good ideas, but i think that the draining of it would be difficult to implement for just one block though. Maybe add other types of sinking blocks like goo, or have it be a type of liquid.
i think that would be better as like goop or something that would just slow down movement and not kill you or have you break your spacebar lol