Hello,
Loving your work.
I've seen a few of the bugs already reported but these two I couldn't see on the known list.
I had an Alien 'stuck' (or didn't move anyway) in the UFO, even when I went right up to him round the back door. I also couldn't seem to shoot him for ages using an M16 sodlier, when I finally did with my pistol guy, I got a game freeze. Now that I'm typing this, it might be similar to the CTD on shooting Alien but the shot never actually reached it, game froze with bullet in mid-flight.
The other one was trying to get upstairs, I was getting the weird clipping issue with the barriers and in the building (also with squares of what looked like fog of war/ shadow on the stairs and walls where there shouldn't have been either) and made me man stand next to the stairs with his back to them. I then wanted him to go up the stairs, so one square left, one square up then one square right (the equivalent of 1,7 then 9 on the numeric keypad, if that makes it a bit clearer) and it took something like 38 AP, no idea how it happened. I'll try and recreate it too.
Other than that, it's looking good and can't wait for further builds / the full game. Keep it up!
EDIT: I seem to have registered wrongly so it doesn't say that I'm a backer