Paths where people walk
The ground turns to flat pixel grass, sandy paths wear in where people actually walk, and people get a soft shadow under their feet.
Worn paths have been in Groundwork for a long time. A tile people walk over often wears down, and a worn tile is a little quicker to cross, so the routes people prefer get preferred even more. But since the switch to 3D you could not see any of it. The paths were only numbers.
So the ground got a new look. Every tile is now eight by eight flat pixels of grass, a few a shade lighter or darker and now and then a white or yellow flower. Where people walk, a sandy strip wears into it. It starts in the middle of the tile, runs toward the next worn tile so the strips join up into real paths, and gets wider the more it is used, with paler trampled grass along its edges. I used a photo of a real footpath across a lawn as the example.
Getting the speed right took a few rounds. At first a path needed about sixty passes, and every quiet day took a sixth of it away again, so one hardly ever formed. Now a dozen or so passes wear a path, and it takes about eleven days without anyone on it to grow back. Standing still wears nothing, so a crowd chatting at the well does not dig a hole, and the ground right round a tree holds out better, so paths go round the woods instead of churning them up.
I also picked the colours with the road plans in mind. A worn path is one plain sandy yellow, a hand-made road will be brown gravel, a stone road grey cobbles and tar dark. With square pixels two shades of grey just look like the same thing, so every kind of path gets its own colour and pattern.
Then the shadows. The sun moves across the sky all day, and because everything is made of small blocks, its shadows flickered at the edges. Two suns now stand still a moment apart and the light slides from one to the other, which calmed the buildings and trees down. The people still flickered as they walked, so they no longer cast a real shadow at all. They get a soft dark spot on the ground under their feet instead, which moves with them and never jitters. A plain shadow is better than a jumpy one.
One more thing you can see in the video: when two people meet on a path, they now each step a little to the side and walk past, instead of bumping apart like magnets.