Although its not a sci-fi title, Romance of Three Kingdoms IX is a great strategy title. You are a Warlord who hires and trains armies, leaders, espionage, build forts, war parties, farm, trade, build relations, etc. AI is very strong (since there is no live opponent). Setting is early China (190AD, but don't let that deter you).
If you love the management options of SEIV you will foam at the mouth with the many options and details this game offers. EBay usually has a few available at $10 less than the norm, since the new release 9 just came out.
Reviews:
http://www.gamespy.com/reviews/february04/romanceixps2/
http://www.gametab.com/ps2/romance.o...gdoms.ix/2313/
[ March 22, 2004, 18:57: Message edited by: Cyclop ]