WAD keys to move. Click on a black platform to launch a rope. Press space to clear the rope. Get to the blue. Red is bad. Falling off the bottom edge kills you. There is no wall jumping, but there's a rope, so I guess that compensates. You can swing using the rope, and clearing the rope mid-swing cause you to fly a little in the direction you were moving.
Thanks to BobPi for the original project Grappling Hook Engine