Ripley played by Ben.
Ripley is the last survivor of a previous encounter with the aliens.
Ben is a thoughtful roleplayer who tries to think through the best course of action within his character concept and the setting. He enjoys coming up with clever ways to justify the success of his plans within the premises of the setting.
Newt played by Jim.
Newt is a young girl who is the last survivor of the LV-426 colony.
Jim is a rather gung-ho roleplayer, interested in action, cool fight scenes, and lucrative spoils over careful consideration or puzzle solving. He frequently acts before he thinks, which includes fixating on his own strange explanations for setting details that the GM hasn't explained yet.
Corporal Hicks played by Pete.
Corporal Hicks is a marine.
Pete is an old friend of Jim's. Jim invited him along to join in this new game. Pete designed a character to maximise all the skills he thought would come in most useful in a space action combat game, at the cost of being a dimwitted, low-ranking grunt.
Private Vasquez played by Sally.
Private Vasquez is a marine.
Sally is Ben's younger sister. Ben took her along to the game on the first evening when his parents couldn't get a babysitter for the night. The GM quickly gave her a character to play so she wouldn't get bored. She enjoys the make-believe aspect of the game, but has some trouble separating it from reality.
Burke played by Annie.
Burke is a representative of The Company, on the mission to oversee company interests.
Annie is an acquaintance of Ben's, who attends his drama classes. She was interested to come along and see what this "roleplaying games" thing was all about, after Ben described it to her as a sort of improvisational acting thing. She is dedicated to playing her character as a real, complex person with motivations inspired by a well-considered backstory.
Private Hudson is a marine who tends to get carried away when things go wrong. Gorman trusts him implicitly, but Newt suspects Hudson is up to some sort of nefarious plotting behind his leader to take absolute power into his own greedy hands. Who is right remains to be seen.
Bishop is an android assigned to the mission to keep everyone out of trouble, which seems to be a very difficult thing to do with marines and corporate goons and little kids around.
Lieutenant Gorman is the commanding officer of the assult force of marines. His main concern is recovering the mystical Lost Orb of Phanastacoria, a powerful alien artefact capable of protecting people from alien impregnation.
Sergeant Apone is the senior NCO of the marine squad. He is 46 years old, and uses his great wisdom and popularity to make snide remarks and crude jokes to his troops. How exactly he gets away with this is a mystery.