Quite good! I think the combat is quite lacking: obviously the wrench feels a bit weak, but personally I think that a cooler change would be to instead make enemies stop moving every now and then. That way, it becomes a game of exploiting the aliens when they make themselves vulnerable, while still allowing them to feel erratic and threatening. Nothing to critique about the graphics: they feel quite authentic and provide good clarity.
Obviously there is a lack of audio, but it almost works. Maybe if you did add it later, focus on ambient noises and the like to add to the atmosphere. Also, the screen shake when getting hit was cool, but a bit overdone: it was REALLY distracting. All complaints aside, really nice job!