What does the phrase "fire a long line" mean here? [closed]

Here is a sentence from an action game:

You need to grapple downward, then fire a long line through a gap.

I am not sure about the meaning of the phrase fire a long line. The preceding sentence describes the importance of momentum in moving across tight passages.

The player has to swing herself to the top of the mountain avoiding different obstacles including collapsing rocks, snowbanks, etc.


Solution 1:

To get a long line to the top of a cliff you need a rocket propelled grappling iron/ grappling hook. These exist in real life: enter image description here

and as props for film and cosplay: grapple and line moviegunguy.com