I really liked I've Got a Secret for a couple of reasons. They could feature segments that didn't really fit Truth or Line, like the 50th High School Reunion from 1915 with the teacher in attendance and the teacher's teacher or the guy that blew up an inner tube until it exploded. I also enjoyed the chemistry on the show, particularly during the Garry Moore years. He and the panel got along great and they didn't skip a beat when Besty and Bess replaced Faye and Jayne. It was more relaxed than Truth and Line could be in their formats at the time.
Looks like they pulled a few episodes to honor those who passed this year with the Nimoy episode and a WML with Frank Gifford. While they've been doing this yearly for quite some time now, I suppose they could bill these episodes of IGAS as a tribute to Betsy Palmer.