Fully visible — but every 25 steps or 12 seconds, the maze redraws itself around you.
Fully visible — but spacetime is unstable, and you're bumped somewhere random every few seconds.
Fully visible — touch a wax seal and the walls around it melt open for a few seconds before hardening shut.
Nothing is hidden — but the ground you started on is burning, and it's spreading toward the exit.
Every few seconds a sandstorm buries the board — when it clears, the dunes have shifted into a new maze.
Fully visible, but the maze quietly redraws around your mistakes and hesitations.