(Image credit: The Derek Sheely Foundation) The NFL has an extremely ugly history with concussions. I won't rehash it all here, but in broad strokes, the American football organization spent years denying a link between head injuries sustained by players and the devastating long-term effects, was eventually sued by more than 4,500 players for negligence and fraudulent concealment, and settled the suit for nearly a billion dollars in 2013. The Madden football series, for their part, included concussions in the games for a few years (in part due to John Madden's insistence), though a less-specific description of "head injury" replaced the term in Madden 13. It's obvious the NFL and the Madden games want to distance themselves from the word "concussion," but now a mod called Modden 26 , created by a non-profit foundation dedicated to increasing awareness of sports-related brain injuries, is bringing concussions back into the game—along with their effects.…