I've cleared another couple of levels and I think I'm about halfway through. It's hard to say because the story doesn't seem to have much of a build. You are this guy, Kyle Katarn, and you are working with the Rebellion against the Galactic Empire. And while there's this overarching arc with the Dark Trooper project, your quest to stop this sinister research is mostly just a matter of going from one place to another and finding the arbitrary point in each level that triggers the end of level message.
I'm not sure how I feel about this Kyle Katarn fellow. The game is trying its best to sell me on him, but I'm not really buying it. When you have Darth Vader toss off a casual line about how resourceful and dangerous your main character is, it kind of comes off like you're trying to borrow some unearned coolness.
Of course, the first-person perspective and sparse storytelling may have something to do with it. Aside from a couple of animated cutscenes, most everything I've learned about the Dark Forces storyline has been in the form of between-mission text briefings, and these tend to focus more on plot than characterization or worldbuilding. And I can't really get any sort of read on the character from his incredible feats of martial prowess or cunning infiltration because I never see him directly. My view of the action is limited to the barrel of his gun.
I kind of wound up thinking of Kyle Katarn as a doofus who gets lost in a maze of corridors and who blunders his way from one puzzle to the next, but I have to acknowledge that that's all on me and my poor gameplay skill. Then again, it's supposed to be a major advantage of the first-person silent protagonist that the player may easily project themselves onto the character . . .