Sci-Fi RPGs

I was just browsing through my RPG collection last night looking at the few Sci-Fi based RPGs that I have.
The original Mekton by Mike Pondsmith, the life path system for generating your background was the coolest!
Deluxe Traveller, the original rules, but in full 8 1/2 x 11 sized books as opposed to the mini books. My favorite edition.
Darwin's World, fairly new... came out post D&D 3.0 and was the first attempt at 'Gamma World' for d20.
Serenity, based upon the movie and Firefly TV series... it is beautifully written but I am not sure the rules system is for me.
Alternity, created by TSR just before they were acquired by WOTC. It really looks to be a great scifi rpg... but I never got to play it.
Dreampark by Mike Pondsmith, simple system... versatile... this would be a great game to introduce new people to role-playing.
Buck Rogers XXV by Mike Pondsmith (again)... TSR published, used the AD&D rules as a basis. Well done. Easy to teach. Accessible to D&Ders... very good game. Highly recommended.
StarWars by Greg Costikyan - original edition published by Westend Games. The beginning of the d6 system. Great game!
So, what Scifi RPGs do you own? Or better still, actually play?
The original Mekton by Mike Pondsmith, the life path system for generating your background was the coolest!
Deluxe Traveller, the original rules, but in full 8 1/2 x 11 sized books as opposed to the mini books. My favorite edition.
Darwin's World, fairly new... came out post D&D 3.0 and was the first attempt at 'Gamma World' for d20.
Serenity, based upon the movie and Firefly TV series... it is beautifully written but I am not sure the rules system is for me.
Alternity, created by TSR just before they were acquired by WOTC. It really looks to be a great scifi rpg... but I never got to play it.
Dreampark by Mike Pondsmith, simple system... versatile... this would be a great game to introduce new people to role-playing.
Buck Rogers XXV by Mike Pondsmith (again)... TSR published, used the AD&D rules as a basis. Well done. Easy to teach. Accessible to D&Ders... very good game. Highly recommended.
StarWars by Greg Costikyan - original edition published by Westend Games. The beginning of the d6 system. Great game!
So, what Scifi RPGs do you own? Or better still, actually play?