In space, no one can hear you scream...

I got the Alien RPG from Free League the other day. It's taken me a couple of days to read through it, but it's a really good book. The game is set up so that you don't even have to incorporate xenomorphs into the game if you don't want to. You could just run an open-ended campaign set in a gritty spacefaring future.
What I'm most jazzed about is the section on generating star systems, planets, colonies, colony missions, etc. Since I've been doing a lot more solo roleplaying, stuff like this is gravy to me.
Looking forward to giving some of the stuff a try, maybe in a solo sci-fi game.