I just loaded my most recent save, and was greeted with this. It looks like the "damage" texture, that is supposed to show up when a block is partially dug or damaged, is instead showing up everywhere.
In this screenshot there should be some generators, pumps, wires, pipes, and so on. Plus there's a volcano in the middle there, and some plants around the edges, which are also invisible. I note that liquids, critters, and floor debris can still be seen.
This screenshot is from right after reloading, before I restarted the clock, however it doesn't change when I let time run. It also doesn't change if I close and restart the whole game.