ARG
n.— «ARGs, as they’re called, use real-world clues—from classified ads to answering-machine messages to URLs that show up in obscure places—to help players solve puzzles so intricate they might take groups to crack.» —“Alternate reality games” by Monty Phan Newsday (Long Island, N.Y.) May 25, 2005. (source: Double-Tongued Dictionary)