How many iterations of the DS have been released?
Nintendo DS family
Throughout its lifetime, Sony's PlayStation Portable has been the main market competitor. There have been four different models of the Nintendo DS line on the market: the original Nintendo DS, the Nintendo DS Lite, as well as the Nintendo DSi and its XL variant. The Nintendo DS line has been highly successful, continuing the trend of its predecessor, the Game Boy line. With over 154 million units sold worldwide, the DS models are the best-selling handheld consoles, and second best-selling console overall behind the PlayStation 2.
Double Dragon
The first game, "Double Dragon", was released in the arcades in 1987. A Nintendo Entertainment System version produced by Technōs was released in 1988, followed by a Game Boy version in . Various licensed versions were also produced by other developers for gaming platforms such as the Master System, Atari 2600, Atari 7800, Genesis, Atari Lynx and for home computers. Two "Double Dragon" sequels were released for the arcade: "" in and "" in . Like the original, Technōs produced versions for the NES ("" in and "" in respectively). A fourth game was released exclusively for the Super NES in , titled "Super Double Dragon". It was the last game produced by the original team at Technōs. The Game Gear game "Double Dragon" is not a port of the original arcade game, but is instead an entirely new entry in the series that has gameplay elements that are more similar to "Streets of Rage".