It's been a while, so I don't remember exactly how long the voxel art took. The main issue is that MagicaVoxel had a severe limit on the size of any particular project, so I had to split things up into pieces, then combine them in unity. However, that did work out in my favor when it came to animating things, because I now had objects like legs and heads which were independent of the bodies. The rat's movement animation is actually replacing all its legs every other frame with ones set in a different position. :D
I spent more time trying to figure out how to keep the player from pushing through the walls, as at the time I had no idea how to use physics for movement. My solution to that was moving the entire world instead of the player, and using teleportation at the entrances to each room to simulate going from one to the next.