It's what developer BioWare didn't do in Mass Effect 3 that makes the space role-playing game such a successful and fitting end to the current story arc.
The game didn't change core elements just for the sake of change. So while many developers look to be revolutionary in sequels, Mass Effect 3 is largely an evolution of the previous two games.
You won't see many new gameplay elements or story devices, but that's what makes it so great.
Combat is probably the element that was improved the most. Commander Shepard, the protagonist, now reacts much more smoothly to controls when he's behind cover. There also are more powers available, and grenades are an option across more characters. These are welcome additions and make the combat a fun and exciting element of the game.
One of the most talked about aspects of this third installment is the ability to import previous saved games and affect how the story and characters play out.
Bioware delivered on it promise. Not only can you import your character, you also get the ability to spend a lot of prior games' skill points, entering the game with a huge bonus. Depending on decisions you made in previous games, certain characters might not even be in Mass Effect 3.
This is amazing from a development standpoint, seeing as how hundreds and hundreds of hours went into creating characters that might not show up at all.
Also featured in this game is something that should be a core element of every role-playing game: The ability to reset skill points. This is crucial to the gameplay because as you advance through different combat scenarios, you will learn which elements of a combo work wonderfully and which don't work at all. Then you can go into the ship, access the console, reset all your points and distribute them as you see fit. This makes a world of difference.
The game's major drawback is the story might not satisfy the legions of fans that his trilogy has. But with such high expectations, it's hard to please everyone.
If you've played the previous two games, picking up this one is a given. And if you haven't, it's worth a look just because of the refinements. It's the ultimate sci-fi RPG and will remain so for many years.