It overall looks nice, but there are a few things I don't like.
There are several dark spots outside the human/alien bases in the tunnel that are very dark. These provide nice hiding spots for aliens, but it is nearly impossible to see if there is anyone inside other than by shooting. The average player will notice nothing on quick inspection, and if the aliens stand still, they will not show upon radar. Given that they are very hard to see, I suggest adding a bit of ambient light there so that humans are not so easy to ambush.
Second: it is no longer possible to do this:
