I recent update has lowered the score necessary for many levels. As such, this level is now ridiculously easy to get par score on.
The new par score is 11k, and I was able to get 14k just by speed-running the level on normal. Feel free to put on the Jacked skull for a point boost, but I didn't use it.
The only areas where you actually have to fight enemies are
- The beginning
-- You have to fight the initial group, another group that comes out a door, two brutes that come up the elevator, and one on the balcony.
- The first grav lift
-- There are several enemies before the lift, as well as a brute and I think 4 grunts that come up the lift
- Saving the marines
-- You have to kill most if not all the enemies in the room before and after you save the marines. You can camp the lifts for most of them.
- The ending
-- The room starts with several brutes, three ultra elites, and a few hunters that run in soon after. You have to kill all these enemies to proceed.
I ignored just about every other enemy during the run. I kept a sword on me at all times and only really fought if there were too many people to run by, or if my sword lunge gave me a boost forward.
The only group I had to fight other than the ones listed was the group that comes out on the bridge, right before the final room.
I didn't have a clean run by any measure of the word, so getting par time on normal should be enough to get you the par score.