Jaern is a system that evolved during a 30+ year (and still going!) campaign. The main mover behind the system was Dan Lawrence.

The Purdue Fantasy Club uses the July 29, 2006 version of the manual and has gone in a slightly different direction than Dan. Our changes (against this version) are available

Fantasy Club Manual Rewrite (includes nearly all local rule changes)
July 29, 2006 Manual
Current Local Rules changes