Use gravity to swing between planets! Look at a planet to target it, and hold click to get pulled in by it's gravity. Didn't have time for any win or fail states, so just have fun swinging around!
Look around with mouse. While looking directly at a planet, hold left mouse button to latch on and gravitate towards it. You can look away while attached to a planet; I'd recommend attaching to planets you're flying along side to get a good orbit.
Hold space bar to adjust sensitivity (there's a slider to the right of the text) and switch inversion of camera controls.