The Mass Effect franchise has taken Commander Shepard all over the universe. Players have mined countless planets and explored dozens of galaxies, but when you think about it, most of those worlds have been more or less the same. The uninhabitable planets described in the short text blurbs of the game's codex always sounded more interesting to me than the standard shooter fare of the franchise's main hub worlds, but we've never had reason to set foot in such uncharted territory. Until Leviathan, that is.

Mass Effect 3's first story DLC takes the Commander where no Shepard has gone before; under the sea. It's an environment that feels more foreign than just about any of the sci-fi tinged settings we've seen in past games, an irony given that it is in many ways the most similar to our own world. To experience something so completely new in a franchise consisting of three full releases and numerous DLC expansions is nothing short of a rush.

But I'm getting a bit ahead of myself. Before you can explore the dark depths of the sea, you will have to don your thinking cap and novelty pipe for a bit of mystery solving. The story of Leviathan has been hundreds of years in the making, if not more, and it tasks you with discovering the origins of the titular Leviathan and drawing him to your side in the fight against the Reapers. This will soon lead you on a high octane chase through several brand new locations before sinking you at the bottom of the ocean.

Being that the central conceit of the expansion is a mystery, Leviathan tasks you with doing a good bit more sleuthing than you might be used to in a Mass Effect game. Before you start thinking up the bizarre lovechild ofMass Effect and Arkham City, though, note that the sleuthing in Leviathan is a good bit more simplified than it has been in other recent action games. You're essentially going to spend your time in a Citadel lab clicking on various items until one of them moves you forward in the story. Yeah, it's a lot less glamorous than it probably should have been, and a lot less fun, too. It's also just a little too prevalent in the story; the button clicking game comes up one too many times over the course of the story, and it kind of kills the momentum every time it rears its head.

Aside from the dull mechanics of it, the mystery at the heart of Leviathan is a strong one. The story is intriguing enough, even if we do all know how it's going to end (after all, Mass Effect 3 had a proper ending and not much we do in this expansion will change that,) and new banter with your teammates adds character to the non-combat portions of the game. It's especially fun to be able to just a little more time with the game's love interest, who all have romantic new dialogue.

The combat sections in Leviathan are equally rewarding, consisting as they do of tougher, higher-level opponents. You will find yourself scuffling with tons of Harvesters, Banshees and Brutes over the expansion's three-hour runtime. Battles don't get as challenging as they were at the end of the game proper, but these encounters with the game's big baddies are just tough enough to force you to strategize. Thinking on your feet has always been the best part of Mass Effect's combat, and it's an aspect of gameplay that Leviathan thankfully embraces.

Leviathan is far from the perfect DLC; the investigation sections are dry and kill all sense of momentum, and we all know that no matter how intriguing the mystery at the story's heart, it won't have any effect on the game proper. But for ten dollars, you get an undersea experience that is completely new to the Mass Effect franchise and a great, self-contained little story. At this point in the franchise's life, that's impressive enough to warrant checking out for series fans.

Score: 8/10

This DLC was reviewed on the Xbox 360