To complete the Wombat Mazes in the most direct route for the fastest score, turn the following directions at each split in the tunnel:

Level 1: Left or right (all paths lead to the wombat and out again).
Level 2: Left, right, (at wombat, turn around) Left, Right, exit.
Level 3: Right, left, right, left, right, (at wombat, turn around) left, right, left, right, left, exit