Board Thread:Questions and Answers/@comment-10184949-20130529153511/@comment-3551173-20130612230322

Well the first anime was divided into two cours or two sets of 12 or 13 which is why an arguement could be made that yes there were two season in the first anime.

season 1 = Aincrad

season 2 = Alfheim

still I prefer the other way of looking at it with the first anime being the 1st season and the GGO when it gets animated being season 2.