by GrandKhan44
The thematic idea was that of a forgotten series on VHS and these are the tapes. So season 1 with 6 episodes is the first base game, season 2 the expansion. They carried this on with season 3 which is a new standalone game and season 4 again an expansion.You can get any of the base games and combine it with all the other stuff. The core rules are the same. Season 3 introduces relics (to make the game easier) and unknown monsters (to make it harder).
You can buy season 1 now in retail, or late pledge for season 3 with lots of Kickstarter extras. For season 3, you will have to wait for at least a year, and nobody really knows how good the new scenarios and the new rules are, season 1 is well known and pretty popular.