Japanese developer Arc System Works has been hard at work on a direct sequel to Double Dragon series in Double Dragon IV, set to release toward the end of this month in time to celebrate the 30th anniversary.Arc System Works worked on the Sega Master system version of the original side-scrolling retro beat-em-up Double Dragon back in 1988, and since has worked on Final Lap, Battletoads, and the Guilty Gear series to name but a few.Double Dragon IV looks like it's staying faithful to the original series, with a visual presentation straight out of the 80s.