Played a highly modified version of Chariot of the Gods (switched an existing SWN game over to Alien and ported the characters over).
Characters found a derelict ship (the Cronus, minus spores and neomorphs) and began to explore it.
In three hours they managed to get from the D deck up to the bridge, only encountering a couple gristly scenes a single abomination that got blown away in a single shotgun blast.
One player pushed to make a roll at every opportunity and his stress skyrocketed. Pretty soon he was stuck in a perpetual panic attack, constantly trying to flee and hide.
In retrospect I should have hand-waved some of the requests to roll, but it worked out. He had really bad luck with his air supply rolls too, running out of air before they cleared the first deck (luckily the found some tanks on the ship) so his character was having a REALLY bad day.
Session cliffhanger ended with the characters reaching the bridge, finding some strange alien growth on one of the window panels. One character freaked out and shot it, blowing out the window.
Interestingly the players refused to hole up somewhere and rest to reduce stress (they started "NOWHERE IS SAFE ENOUGH" even though they've only come across a single monster), so all of them are sitting on like 5-8 stress.
EDIT: One house role: I added a jenga tower; whenever a PC had to do something 'scary' they pulled a block. If they abandon a pull they gain a stress and the PC chickens out. If the tower falls it triggers a crisis.
So if a PC wanted to check out a storage closet, I'd tell them to pull a block. If the tower falls maybe there was a monster in there. Added some fun anxiety at the table!
Amusing the tower fell when the PCs were in a hallway arguing about which way to go and someone bumped the table. Suddenly the argument is cut short when they hear something around the corner...