It does specifically ask for a "Perception check" at one point, and makes heavy use of easy, medium and hard DC checks, neither of which translate over to a system like Mothership very well and are very DND-centric
Not really. GURPS has a Perception stat that's derived differently than D&D and can differ per sense if a character has specialized in better hearing, sight, etc. Perception checks are very much a part of GURPS. Savage Worlds has a Notice skill that acts almost 1:1 to Perception. GURPS and Savage Worlds (and lots of other games besides) both also have the concepts of "easy", "medium", and "hard" checks.
That there are some systems that do not have a Perception style mechanism does not mean that the adventure is "DND-centric", that just means you're running a system that probably doesn't act as a simple translation target for the adventure.
