No, you didn't carry any weapons, it was a group of like 10 people following a couple of marines thru the base.
You start like you were just going to take a tour of the base, were they kept the Aliens and made experimentes with them, but as he is explaining you what you were going to do, the alarms went off, and the aliens break out, so you have to start running following the Marine who is shooting aliens left and right (Very realistic Aliens mind you, like real people in alien suits just like the movie).
And I remember there was this part were you would all go inside this big elevator, and it got jammed, all of the sudden the doors would open again and an Alien would come in and grab one of the tourist and take him away.
This ride was scary and intense, it really made you feel like you were in Aliens, running thru the facility.