The reactions to the end of Mass Effect 3 fall into two camps. There's the "The end was literally worse than 1000 Holocausts" camp, and there's the "What game were those guys playing, I thought it was fine" camp. I fall into the second camp, and here is why I think the ending works.
First we have to talk about video game endings as a whole. Games are a new medium, and so there aren't really many established rules for their structure. In old-school storytelling, the classic structure of an ending was the Climax. Here the main conflict is finally resolved, and the protagonist's arc is over (think Star Wars, the king of simple classic storytelling). Obviously many great works of art do not follow this basic structure, but they always do so for a specific reason. A good example of this is Monty Python and The Holy Grail. Instead of ending with a big final battle, the film ends with the characters being arrested and a sudden cut to black. The Pythons break the rule because it's funnier that way.
Despite being a new medium, games have actually settled on their own sort of "classic" structure. They begin with easy levels to teach the basic mechanics, they continue with more challenging and varied levels that force the player to learn new mechanics and explore new ways of using the old ones, and they end with a Final Challenge. During the Final Challenge the player must use everything they've learned so far to pass a test harder than anything they've faced before (think of the Bowser's Castle level in every Mario game ever). Games can, and should, not follow this structure, but they must do so for a specific reason.
|The Star Wars of video games.|
The Mass Effect series follows the classic storytelling structure to a T. There is protagonist, a central good vs. evil conflict, and a general rising action to a final climax. As a game, however, it doesn't work quite as well, primarily because it fails to follow the classic video game structure so frequently and without good reason. The game is really two games in one: half the game is Heavy Rain, where you walk around talking to people and making important choices that affect the narrative, and half the game is Gears of War, where you run down hallways shooting things. The first half of the game is the most effective, primarily because it follows the classic game structure pretty well. As you go on you make different and interesting choices, which become more complex as the story progresses. This the more engaging gameplay mechanic because it makes the player grow and change with the protagonist, immersing them in the story. The second half of the game is much less engaging because there is so little change. You start out running down hallways with chest-high walls shooting things, and you do that throughout the entirety of the games.
|Because you've never been able to this before in a video game...|
Now back to my main point, the ending. The end of Mass Effect 3 is so successful to me because it follows the classic video game structure so well and so effectively. The first ending we experience is the end to Gears of War-style gameplay, where you have to protect the rockets aimed at the Reaper from the onslaught of Reaper forces. The level is one of the few stand-out shooty levels in the Mass Effect series, because it actually changes the gameplay by raising the stakes to absurd levels. By forcing you to battle more high-level enemies than ever before it really made you feel like this was the final battle, more so than any of the levels before (hooray for storytelling through gameplay!). It works really well as a Final Challenge for that part of the game.
|This is seriously one of the most terrifying enemies ever.|
Of course, that wasn't the part that got so many video game nerds' panties in wads. That was the real ending, where the robot hologram kid asks you to choose the fate of the universe. There is a discussion to be had about whether the ending reconciles the themes developed throughout the larger story, specifically the whole Man vs. Machine idea. But Mass Effect isn't a film (though at times it seems to want to be), it is a video game. In terms of gameplay, the ending is nothing short of brilliant. The primary game mechanic throughout the Mass Effect series is making choices. You choose the fate of civilizations, you choose the fate of your squadmates, and you choose who you want to bang. The ending of Mass Effect 3 is then the perfect Final Challenge for the game. It is a boss fight of choice. You face the biggest, most important choice you will make throughout the course of the game, and, like all good boss fights, it isn't easy. There is no "defeat the Reapers, bang Liara, live happily ever after" choice. Each choice has serious consequences for the universe.
|Blue. No, Red! Aaaaaagghhh! [is thrown off cliff]|
A good fantasy is never really about what it is about on the surface. Star Wars is not about the civil war between the Rebels and the Empire, it's about a son overcoming the sins of his father. Lord of the Rings isn't about the fight for Middle Earth, it's about good overcoming evil. Harry Potter isn't about the wizarding world dealing with Voldemort, it's about love conquering everything. Despite what many fans like to think, Mass Effect is 100% a fantasy (yeah, keep telling yourself that the race of sexy blue aliens who want to have sex with everyone is "science fiction"). It's not really about the conflict with the Reapers, or even the conflict between synthetics and organics. It's about choices, and how the choices you make define you. It doesn't always do the best job of exploring that idea, but the ending hits it out of the park.
|The best of all possible endings.|