This is level 9 of the Low-power Tunnel.
This level is easy. If it had no darkness it could replace Level 2. Just turn up the brightness and have fun.
You can find out where the walls are by looking at where the stars are. All the walls are on the left side of the platform you are standing on.
Overall, this level is really easy. So cherish it. The later levels of this tunnel will be very hard.