I feel kind of dumb suggesting this because I have nothing to contribute but ideas here (unfortunately I can't sprite, code, etc) but I think some of the progession is kind of wrong. Shooting down HKs as the main conciet of the game is actually a novel idea, and makes sense given the fact that they seem more like attack helijets than anything that could really hold its own in a dogfight. Even though the mod seems to be having the same issues for me as the dude above, that first couple of interceptions was really intense and seeing an HK through the scope was wild. My game crashes unpredictably after a few minutes of play though.
I did get one ground mission done, and while I like it, facing Terminators, even T-600s and earlier models right off just feels wrong. I always imagined that the HK Aerials and HK Tanks we see in the movie were the real forces of Skynet's arsenal. If Skynet would fill its craft with defense drones, they'd probably be compact, especially the early ones. Small, weakly armored, lightly armed, dare I say "boring" robots that are basically just a machine gun or rocket launcher on treads, kind of like some military prototypes today. The Terminators are supposed to be "The newest. The worst." Chris actually discussed this on one of his musings, concluding that Skynet's arsenal must have started out with more recognizable robots first and moved to Terminators later. Chris's intial conception of Skynet's first drones are as tiny rodent-sized poison needle-shooting paranoia machines, which I would imagine is next to impossible to emulate in XCOM. Some of the robot artwork from the original Wasteland videogame might be a good cross-reference if I had to point to anything else that tried the abstract robot route.
I don't really think James Cameron actually thought the whole scenario all the way through like this, so it can be argued a lot one way or the other, and Terminator 2 definitely implies the Endoskeletons fought on the front lines so who knows. Also, I know what I'm suggesting would entail different sprite work and probably a significant change in mechanics to accomodate it, so please take this as friendly input and not demanding. My jaw just about hit the floor when I even heard there's a Terminator mod out for OpenXCOM, and I have no doubt that once its finished it'll probably be the closest a Terminator game will ever come to the Fight For the Future even if it remains a strict XCOM clone. This is a bit of fantasizing, mostly. Though when it comes to sprite work a box on treads with a gun sticking out of it might be easier to draw and animate than trying to invent 6-8 unique Endoskeleton variants.
Either way I look forward to seeing where this goes and I hope the issues with the mod get ironed out. I'm surprised anyone else even knew about Chris's website let alone was basing an XCOM mod off of it (will the Buster show up?) but I suppose Terminator fans really stick together more than I thought. Love the redesigned Geoscape by the way, instantly puts me in the mood.
(PS: To whoever put the soundtrack together, the music from the first movie used is taken from The Definitive Edition, which sounds a little bit different from the movie's actual soundtrack. Brad Fidel did a closer version to it later, though some tracks sound better on The Definitive Edition since its basically a remix. Not a really a criticism, I enjoy both versions, I just figure its only a matter of time before some music snob points this out so I figured I'd beat them to the punch.)