Personally, I think it's worth it to buy all the console versions of the Ace Combat series so that you can see the plotline evolving. Well, except Ace Combat 3, which was a game on massive scale (think Final Fantasy 7 kinda thing) in Japan, but was cut to bare boring minimum for the NTSC versions. Tragic shame. (Also, "Ace Combat 1" is actually called Air Combat. Don't ask me why.)