The title of the show is a reference to the "SD Gundam", or Super-Deformed Gundam sub-franchise, though for this show, SD stands for Superior Defender. It is a crossover series based on the three SD Gundam settings that were used in earlier SD Gundam anime and manga: "SD Command Chronicles", a science-fiction-styled militaristic setting; "Musha Gundam", a setting with samurai-themed robots; and "Knight Gundam", a medieval European fantasy-themed setting. It also contains many references and homages to the standard Gundam shows, especially those of the Universal Century, Future Century, and After Colony timelines. In a sharp contrast to the dark nature of most of the other Gundam series, "SD Gundam Force" is relatively lighthearted, though it does at times get more serious as the series goes on, it is never as dark as the more "traditional" Gundam series.