Awesome work
I had this board game as a youth and it was awesome, played it all the time. You did a great job replicating it. Here are my only suggestions/wishlists:
1. "A marine has a 00 chance of hitting a target." That was on a 10-sided die in the board game, so you actually had a 1 in 10 chance of hitting with 00 (on a 10-sided die 10 is indicated by 0). As far as I can tell, a marine in your version cannot hit a target when 00 is indicated. So I think your aiming system is off by one unit. For example, in the board game, Hicks needed a 7 or lower to hit an alien with his shotgun at one space, but "10" equaled zero, so he'll hit that alien 8 out of 10 times. If I'm wrong, I apologize, but I think I may be correct.
2. In the board game, there were optional rules that you should definitely integrate: The Apone rule, Frost rule, and Dietrich rule. There was also a stairway rule. As I recall, the board game starts out with the requirement that the team cannot move past the right edge of the center stairwell for 5 rounds. Additionally, at any time a marine in a square adjacent to the stairway is grabbed, then freed by his comrades, there was a chance he might stumble and fall over the railing and plummet to his doom. Aliens that were melee'd off the stairwell were also considered killed (though I always thought they'd probably survive the fall)
Apone rule: If Apone is captured, no one can move for 3-4 turns (not sure if I remember that right).
Dietrich rule: If a marine with a flame unit is grabbed by an alien, there is a chance they will accidently trigger their flame unit. If the flame unit was accidently triggered, one square surrounding the grabbed marine was be flamed. Aliens or marines in adjacent squares could be hit and would be killed accidently.
Frost Rule: Obviously, if Frost is accidently (or purposely) flamed, an explosion equal to a grenade detonates from his space in 2-3 turns.
3. It would be cool if you gave the option to not surrender the ammo in the reactor (just for fun, the game would not continue on if that option is chosen).
4. Put Ferro and Spunkmeyer in there as options, why not? I know you said in a previous post that you didn't want to mess with the integrity of the original game, but I must mention that the board game didn't have an ammo counter. If you want to take it a bit further, I always though Hudson should have been a 3-action character or at least have Vasquez's accuracy with the pulse rifle.
5. Picking up weapons. One of the coolest parts of your game is that you see the captured marines rifle/flame unit on the ground after they're carried off. Why not give a marine walking through that square the option to pick up the weapon (except the smart guns). Drake actually does this in the reactor in the movie (I believe he picks up Apone's flame unit, and uses it at the end of the retreat).
That's all I've got. I'd love to hear your thoughts on these. Again awesome job!