Variety is reporting that Bryan Singer has decided to direct a remake of Logan's Run, based on the science fiction novel by William Nolan that inspired a popular 1976 film adaptation. The original movie version of this saga of a youth-obsessed future society changed the age at which everyone faces mandatory termination from 21 to 30.   Singer plans on returning to Nolan's original concept of termination at 21, which will make this new version of Logan's Run a great vehicle for a young actor.  No casting decisions have been announced, but Warner Brothers plans on releasing what producer Joel Silver characterized as, '...a huge sci-fi adventure film' in 2005, so casting and production will have to start within the next few months.  According to Variety, Singer will direct the Logan's Run remake at Warner Bros. before returning to helm X-Men 3 at Fox.