Every time you walk into a new chunk, the whole thing turns into one random block. Wool, stone, glass, whatever.
A block can't show up again until 100 other ones have been used, so you get a lot of variety.
Air stays air, so you won't get stuck inside a wall. Bedrock, water, lava, chests, furnaces and portals aren't touched.
Needs Fabric API.
Heads up: it really changes your world, so try it on a new one or back up first.
I look forward to your comments!!!!
