The 'Grapple' is an infinitely ranged player-to-point utility item which is capable of bringing the user closer to the things it's fired at -- it is core to performing advanced maneuvers and navigating out in 0g.
LMB and hold to shoot grapple. It resets when you release
Hold RMB while grappling to pull you towards the grappling point -- it is more effective in 0g than it is in normal gravity
- The grapple line contracts as you get closer to the pivot, but never expands -- so when swinging around an object, make sure to give yourself enough space for the arc.
The 'Secondary Fire' does nothing without a ball attached to a target surface.
(guides for this item will be linked here)
Building up Speed
One method for building up build up speed is to first charge a jump, then release it and quickly grapple downwards. Doing so will convert your jump's vertical speed to horizontal speed. This process can be repeated as long as there is space to continue: