I finally found the Line Gun this playthrough. My favorite gun in the entire game, though the Contact Beam is awesome as well. The Force Gun is a close second. Anyhoo, took out the regenerating beast after having to escape him multiple times. Sent his frozen but up a couple of levels (I think).
Alright! It was tough as I had a hunter alien on my heels the whole time, but I was able to reach Nicole, who was attached to the Marker. I defeated her (eventually) and made my escape with Ellie. What a cool game. Final boss and game ending! Great stream!