Originally published over twenty years ago, in 1984, Masks of Nyarlathotep is one of Chaosium's best known campaigns for good reason. Not only does it provide a wide geographic variety of adventures players and Keepers will enjoy, it's also a very well designed adventure, avoiding many pitfalls other Call of Cthulhu adventures fall into. Masks was written by Larry DiTillio, whose writing credits also include executive story editor for the science-fiction series Babylon 5.
The adventure begins with the gruesome murder of a friend in New York. Investigators explore overseas to England, Egypt, Kenya, Shanghai, and western Australia. Locations range from London museums, to Egyptian pyramids, Kenyan mountains, Australian deserts, and Chinese import warehouses. NPCs run the gamut from high society to mysterious wisemen. Not only will investigators encounter cults dedicated to different aspects of Nyarlathotep, but will meet a memorable variety of mythos creatures as well.
From a Keeper's standpoint, the adventure is exceptionally well-designed. All too often, I've run a Call of Cthulhu adventure only to hit an unexpected dead end, as the players failed to find a critical clue called for by the adventure. Some fumbling improvisation usually moves the plot forward, but the author in Masks provides multiple ways to obtain the clues the investigators need to proceed in their tasks. For those Keepers who enjoy adding their own touches to an adventure, the author suggests various adventure seeds to enhance game sessions. Meanwhile, Keepers who do not will not be required to do so. Each country has three to five separate adventures, including red herrings, which investigators should encounter more often than they seem to do. If there's any caution to note, Keepers should be prepared to play the part of a very wide range of NPCs. If you have a co-GM, or a player who's joining for just one session, enlist them to play a few NPCs!
In my opinion, I think the PDF format is superior to the dead-tree version. Both hardcopy and PDF have a handout section that can be photocopied or printed out. However, with a PDF, a Keeper can do much more. The Keeper can print out maps and 1920's prices for players to refer to. The adventures contain atmospheric evocative artwork the Keeper can print out to show the players what their investigators see. Players inevitably forget the orally presented (and often critical) information their investigators discover. The Keeper can print and give this information to the players. And, when PCs also inevetibly expire, NPCs encountered in the adventure can become PCs. The Keeper can print out their stats and backgrounds to provide them to the players. If a player misses several sessions, or a new player joins in a few months into play, the other players can simply give the handouts to the player to catch up (assuming they're organized better than your typical Arkham professor's research notes).
I'm very happy to see Chaosium release Masks of Nyarlathotep in PDF format. Its $20 pricetag is also 2/3 the price of the dead-tree version. Not a bad deal for one of Call of Cthulhu's mostly highly regarded adventures.
[5 of 5 Stars!]