It might surprise you to learn that All 4 One has the longest campaign in the series by play time. It didn't surprise me, however, because this game excels at dragging on. The story takes an interesting approach putting the squad on one planet and having the whole adventure be in once location, but I didn't care enough about the plot by the end of it to give a satisfying ending. The enemies all feel like sponges for most of the weapons, and there's very little reason to use anything but the Critter Strike once it's been upgraded. A mediocre experience that I'm sure is enhanced by playing alongside others, but definitely a spin-off that need not be revisited.