Competition Series of modules for Advanced Dungeons & Dragons.  Modules C1 through C5 were specially designed for competition play, where certain actions net the player a specified number of points.  Module C6 describes how to run an official RPGA tournament.

C1 Hidden Shrine of Tamoachan by Harold Johnson and Jeff Leason
C2 Ghost Tower of Inverness by Allen Hammack
C3 Lost Island of Castanamir by Ken Rolston
C4 To Find a King by Bob Blake
C5 Bane of Llywelyn by Bob Blake
C6 Official RPGA Tournament Handbook by Daniel Kramarsky, Jean and Bruce Rabe

C4 To Find a King and C5 Bane of Llywelyn form the "Prophecy of Brie" series, and were originally published as RPGA modules 5, 6, 7, and 8, in Polyhedron newsletters 16, 17, 18, and 19, respectively.  Both modules come with a double cover (module booklet nested inside two covers of maps).  Thanks to Eric Pass for help with this info.

Printing Information

Modules C1 Hidden Shrine of Tamoachan and C2 Ghost Tower of Inverness each have multiple printings, described on their respective pages -- follow the links to them.  Modules C4 - C6 have no distinguishable printings.

C3 Lost Island of Castanamir

• First:  ISBN and Product Number are stacked above the UPC bar code on the rear cover.
   
• Second:  ISBN (only) is within the UPC bar code on the rear cover.
  
  

Thanks to Adrian Newman for this info.

   None. 

• C3 Lost Island of Castanamir
• C4 To Find a King
• C5 Bane of Llywelyn
• C6 RPGA Tournament Handbook