Starshot - Space Circus Fever
The documentation says to double-click the jump button to fly.
Actually, you need to hit the jump button and then double-click
quickly--three taps on the jump button in all--before your
character hits the ground.
When in doubt, try a quick pan with your camera-view controls. A
new perspective on your situation can often be enlightening.
Unless you have a gamepad, which is probably the best alternative,
I recommend joystick controls. It gives a finer touch on the
controls than the mouse or keyboard, and you can configure the
buttons to suit yourself.