It's "stand alone" but how much of the original game does it include? Don't laugh. I haven't played SINS before. I know there were some expansions released for the core game. If I buy "Rebellion" will I get any of the other expansions? Like is this a sort of "Gold" or "GOTY" release? Will I miss anything from the original release? Thanks.

Its an entirely new game that builds from the first three games. It doesn't include anything but it has all the features of the Original, Diplomacy, and Entrenchment as a foundation and Rebellion is the new stuff. One game, not one game and two expansions.

You don't have to buy anything with this game and it will have all the features of the original three games and a bit more.