Mass Effect 2 takes the bleak vacuum of space and flushes it with color--the light of stars and galaxies, the red and violet swirls of far-off nebulas, and the glimpses of comets as they burn through the void. You’ll catch your first glimpse of this in the game’s intense and much-improved art design, but that dance of light and shadows is also an apt metaphor for bleak undercurrents in the story, as well as the moral quandaries and past indiscretions that haunt the main characters. More so than its predecessor, Mass Effect 2 possesses an identity, and most of the obvious changes and improvements over the original are beholden to the shift in tone. The shooting is more immediate and satisfying, which keeps the pace moving and intensifies the violence of each encounter. Rich characterizations invite you to look more closely at each crew member's personal stake in the sprawling galactic backdrop. Even the relatively predictable space opera that is the main plot has sinister moments, and you sense the characters struggling with that heavy burden. Mass Effect 2 is incredibly enjoyable, but it's more than just fun: It's a stellar package with a fierce spirit that makes it engrossing and unforgettable.

Mass Effect 2 begins with dire events that foreshadow the game's darker tone--an attack that leaves the SSV Normandy in pieces and the fate of series protagonist Shepard temporarily unclear. Never fear: Shepard returns thanks to the efforts of the controversial pro-human organization called Cerberus and under the watchful eye of its chain-smoking overseer, The Illusive Man. Entire human colonies are disappearing without a trace, and Cerberus needs you--as Shepard--to investigate and confront the vicious forces behind the mystery. Whether you make your contempt for Cerberus' questionable methods clear or espouse the organization's manipulations, you owe The Illusive Man your life. Like it or loathe it, he casts his shadow on every action you take.

A race of locustlike beings known as the Collectors cast an even larger shadow, and the threat they pose is greater than may first appear. Cerberus wants you to assemble a formidable team to assist and provides you with two human officers of its own. First, there is the sexy Miranda. Then, there is Jacob, who seems initially reticent but allows his emotional fire to burn more brightly as the journey progresses. One by one, you build up your crew of specialists to complement them. Among them are a stoic but powerful Asari named Samara, whose ethical code is as unforgiving as it is inflexible, and Thane, a brooding assassin that belongs to the reptilian Drell race. These are great characters, as are other members of your team, though the Salarian scientist Mordin Solus is possibly the finest character in Mass Effect 2 and arguably the most interesting one seen in an RPG in some time. His ultracaffeinated, ultralogical delivery is often hysterical and always entertaining (his romantic advice will have you in stitches), but his moral misgivings and humaneness make him more than just comic relief. This diverse team joins you aboard a newly built vessel named, appropriately enough, The Normandy SR-2, with the ever-reliable and ever-feisty Joker at the helm. He's not the only blast from the past to cross your path in Mass Effect 2, but it's best to discover for yourself which characters from its predecessor (and what role they play in this trek across the Milky Way) you'll meet again.

Your new boss needs to speak with you. Quick, look busy.

The main plot is conventional science fiction that draws to a predictable close, so the narrative wonders don't exist within the sturdy-but-safe central story; rather, they gild its periphery. Each recruit offers a quest of his or her own to undertake, and these missions give you a lot of insight into your crew members--even those, like Jacob, that seem rather boring initially. Not all of these missions involve combat, which doesn't always work in the game's favor; one in which you follow your target from a walkway overhead is one of Mass Effect 2's weaker moments. But even the rare missions that are light on thrills are still heavy on character development. Writing and dialogue are top notch, keeping each teammate from being a simple sci-fi cliche. The game may come with an M rating, but it doesn't flaunt its adult motifs. Profanity and sexual themes are handled maturely, and their use has purpose and poignancy. There's nary a weak link in the tremendous voice cast, so each line sounds heartfelt, and great facial animations (especially among the nonhuman members of your crew) and physical gestures make it easy to connect with your cohorts.

Conversations commonly present you with a number of responses that affect the meters representing two sides of the ethical spectrum: paragon and renegade. These meters are handled separately rather than represent sides of a single gauge. This structure makes a simple but important point: Morality isn't an either/or, good/bad attribute, but it allows for shades of gray in which to maneuver. As these meters fill, new conversation options open, giving you additional ways to solve dilemmas. These choices don't lead to the complexity and flexibility you see in RPGs like Fallout 3 or Dragon Age, but they result in some electric moments, particularly during the final hours. If you import your character from the original Mass Effect, the decisions you made in that game will be manifested here in extraordinary ways--though it might take a second play-through for you to really understand exactly how extraordinary. A more immediately noticeable adjustment to the conversations is the addition of interrupt triggers. In certain cases, you may get a prompt allowing you to interrupt the scene. This may involve pulling a gun on an unsavory mercenary (a renegade action) or snatching an impressionable youngster from the clutches of a gang when he tries to enroll (a paragon action). These instances have a nice feeling of immediacy and prove that actions really are louder than words.

Purging the galaxy of evil, one Collector at a time.

Mass Effect 2's third-person shooting action is greatly enhanced over the original, making battles exciting and violent, which befits the overall shift in tone. Battles play out as they do in a typical cover-based shooter like Gears of War, with a few caveats (you can't tumble, for example). Sliding into cover is slick and easy, as is popping in and out to take potshots at the wide variety of foes that assault you. Action sequences still present a few rare hangups; you may suddenly rise a few feet into the air for no reason and be unable to move. Or you may get stuck on an invisible obstacle and jitter back and forth. Uncommon bugs aside, Mass Effect 2 works well as a shooter, and other changes to the combat reinforce the improvements. For example, your shields and health automatically regenerate as they commonly do in straightforward shooters, and you now pick up ammo from the battlefield. You can still pause the action to let loose biotic-powered fury, but combat remains fluid and stimulating. It helps that the two teammates accompanying you on your missions are much less of a burden than before--not quite brilliant, but certainly smart enough to stay out of your way and stay alive.