From the contents page:
Challenge, the magazine of science-fiction gaming, is published monthly.
About the Cover: "From this moment on, you will do as I bid," were the last words that Martin Spade heard before his mind clouded and his vision grew dark. Martin's friend, Carla, strains to glimpse the process the insectoid extraterrestrial is using to subvert Spade to its own, dark purposes in this Dark Conspiracy scene brought to us by artist Nick Smith.
With this issue, Challenge went monthly.