The MountainCar-v0 environment simulates a car in a one-dimensional track, situated between two hills. The simulation starts with the car placed between the hills, as shown in the following rendered output:
MountainCar simulation—starting point
The goal is to get the car to climb up the taller hill—the one on the right—and ultimately hit the flag:
MountainCar simulation—car climbing the hill on the right
The simulation is set up with the car's engine being too weak to directly climb the taller hill. The only way to reach the goal is to drive the car back and forth until enough momentum is built for climbing. Climbing the left hill can help to achieve this goal as reaching the left peak will bounce the car back to the right, as shown in the following screenshot:
MountainCar simulation—car bouncing off...
