It's a 160-page d20 Modern supplement that updates the original DarkMatter Campaign Setting (created for the Alternity Science Fiction Roleplaying Game), making it fully compatible with the d20 Modern rules. It also includes some new content.DarkMatter is a world where devious organizations scheme for world domination, otherworldly forces infiltrate our power structures, and creatures from our nightmares lurk in the shadows. Working for a clandestine organization called the Hoffmann Institute, heroes explore hidden mysteries while eluding forces - both human and alien - that scheme to control the truth.