@playmedusa well, turns out the pico8ish 3d engine you wanted was in development when you posted this thread. Demo here:
@playmedusa
In some kind, minecraft can be something like this:
I recently played a game within minecraft with some riddle rooms that were floating islands, where you have to collect items etc. triggered by redstone hidden under the island.
The render range was low and you could teleport from room to room via preassure plates and command blocks.
If you familiar with minecraft, it can be a 3d game engine to walk around in.