The idea behind the first Army of Two was its focus on co-op; and really, was there any other way to play it? The 40th Day builds upon the first game through an expanded weapon customisation system, improved multiplayer and... moral choices?
The 40th Day gets the 'big things’ right. As a shooter it plays fairly well, even if the combat mechanics are only separated from other third-person shooters by about three features (The aggression system, GPS and weapon customisation, all of which were in the first game).
Despite the core gameplay being fairly decent, my experience with The 40th Day was riddled with small annoyances. I was surprised to see that features we take for granted like subtitles, skippable cutscenes and choosing the way to split the screen were absent, and it seems a number of small (though annoying) bugs have slipped through the cracks. There is also no option to change the audio mixing, which, by default, makes it rather hard to hear the voices in the game and try to decipher the plot.
The story puts the players in Shanghai under terrorist attack. This means that the globe-trotting of the first game is out, but there is a surprising amount of variety in the levels. There are radio logs as well, but those feel completely out of place except as collectibles.
As mentioned, there is a morality system. It feels more than a little weird that cuffing an unconscious enemy in a burning and collapsing building is a good deed (at least, according to the game), but the true meat of the system comes at the end of each chapter/level. Players are presented with a choice between good and evil, with the results of their choice showing up as a brief series of slides. It is interesting that the first player to push the button decides, but the rewards and penalties for the decisions all feel somewhat lacklustre.
Still, The 40th Day is still a blast to play with (and should only be played with) a friend in co-op.