State of Decay: Breakdown is the first of two currently-available DLC expansions by Undead Labs and published by Microsoft Games for their zombie survival game State of Decay. You can read the review of the base game here. This is a short form review because, frankly, there isn't much that Breakdown really does to expand the formula too much from the base game, and it isn't worth rehashing.
Breakdown is more characterised by what it removes,
rather than what it adds
So let's just get this out of the way from the onset: Breakdown is just the base game, stripped down to just the sandbox. As a DLC, Breakdown is basically designed to give State of Decay additional playtime by removing the story, and instead giving you a meta progression via achievements in leiu of that story progression, and the endless sandbox as opposed to one with a distinct end point.
This change begs the question: can State of Decay thrive on just the sandbox alone? A game like Fallout 3/New Vegas or the like with an expansive sandbox, fun characters, or the modding capabilities that Fallout 3 has. Unfortunately Breakdown doesn't offer anything new here: all of the characters are characters from the original State of Decay, as is the environs, so there isn't anything new there.
The chief actual addition is more playable characters
Breakdown isn't entirely money for old rope though: there is a selection of unlockable characters via those achievements and while the lineup is entirely old characters it does include quite a few which were never playable, such as Eli, or the courthouse Judge. There's also a selection of new weapons to add some variety to the game. The overarching meta-game, playing over and over again hoping to unlock more characters and increasing levels of difficulty. Given new characters or locales, this would probably be enough of a breath of fresh air to stand on it's own. As is, however, it feels like a holding pattern. The new melee weapons are fewer than one would hope, there's no addition to enemy variety, and that coupled with it being in the same sandbox just leave it feeling very samey.