Defense Grid II is more Defense Grid. It's a tightly-tuned, gorgeous tower defense game set against an epic science fiction backdrop where you commit mass genocide against a host of alien baddies in order to protect your base(s). It's also really good. Except maybe not as good as its predecessor. Or maybe just too similar to its predecessor. It's hard to tell.
I know your face
In terms of the amount of content built for Defense Grid II there's more than enough here to call it a sequel. There's a decently-long campaign with a fully-voiced story that plays out a bit like a weird radio drama (considering you never see any of the characters who are speaking). Like Titanfall earlier this year, the all-audio format makes it next to impossible to keep the characters and plot straight, so...good luck. Minute-to-minute the dialogue is quirky enough though that it doesn't really matter.
But from a mechanics level, Defense Grid II just feels like an expansion. That's no fault of the developers--there's not much you can do with the tower defense genre, which is why the original Defense Grid was so surprising to begin with.
Defense Grid II plays almost exactly like its predecessor though. The big thing that set the original apart--the ability to build new paths with your towers in order to force enemies into longer, more circuitous routes--returns. In fact, Defense Grid II doubles down on the labyrinth-building aspect of the game by adding in a new "Boost Tower."
The Boost Tower isn't a weapon, per se. It's a box. A crate. It doesn't cost much compared to building an Inferno Tower or a Cannon or what have you, so you can throw down a bunch of them with relatively little overhead and build out the walls of your shooty-death-trap. You can also build guns on top of Boost Towers, and then upgrade said Boost Towers to inflict more damage.
That's really it, though. That's the big addition to Defense Grid II, plus the new campaign, plus the new multiplayer modes (if you think you're good enough to compete). It's not a bad value, per se, but if you've already played hundreds of hours of the original Defense Grid there's no magical spark here to bring you back, no surprises lying in wait.
And there are some parts of Defense Grid II that I think are actually weaker than the original, particularly when it comes to split-second judgments. Tower defense is, at its core, a strategy genre. Strategy relies on information--on knowing the right information at the right time.
Defense Grid II is remarkably bad at conveying information to the player. Tower types are hard to distinguish from each other and alien types are even harder to decipher. When you're looking at a mass of twenty oncoming mobs and trying to figure out "Are these the fast ones Are these the ones that turn invisible" then there's a problem. That information should be immediately apparent. The same goes for "Is this my cannon tower Oh wait, no, it's this one over here."
I don't know what the problem is, because I don't feel like I had the same issue with the original Defense Grid. There's something about the way it's laid out though, or how far out the camera is, that makes the game less playable than its forebear--even though it's ninety percent the same game.
Defense Grid II isn't bad. It's actually really good!
But do you understand how a game can garner a good score and still feel sort-of mediocre Or not mediocre, but familiar. Familiar doesn't cut it in the tower defense genre anymore--especially considering that the tower defense genre isn't lighting a fire under anyone's ass these days. The days of that craze are mostly behind us.
The original Defense Grid managed to get people momentarily excited about tower defense again by being something unique and different from the crowd. Fair or not, Defense Grid II needed to pull off the same magic. It doesn't. It's just another (excellent) tower defense game.