The final battle is an essential piece of any game. The culmination of the game's events, the resolution of the story and the payoff of your character's growth, the ultimate showdown and test of strength. I think it's even more important in games than in other mediums due to the presence of player agency, serving as a vehicle to utilize all of the skills you've earned and learned up until that point.
Let's visit a personal favorite of mine. While it may not be the greatest final series of levels - there are more bombastic and better put together final stretches out there - it holds the distinction of working excellently on a very fundamental level, hitting all of the notes that it has to to function as the game's finale.
I'm talking about Sigma's Fortress, from Mega Man X.
This is such a perfect culmination of everything that the game has been leading up to. Let's break it down piece by piece.
After defeating the eight mavericks working under Sigma, you meet up with Zero, who you haven't seen since the beginning of the game. He informs you that he's found Sigma's Fortress, making good on what he promised to do the last time you saw him. The two of you storm his fortress together, with Zero going off first to "keep the main defense force busy".
You first find yourself in a futuristic city, and then scale your way up a mountain via floating platforms to finally enter his fortress. I love this - you don't beam right in. You physically infiltrate his fortress, which is hidden inside of a mountain, which has a very narrow entrance access. This tells you why it took Zero so long to find the place. The music also helps with this - it's not a bombastic, in your face tune like the more famous Wily Stage 1. It's a slow, determined melody that picks up over time. This shows both the infiltration aspect of this stage, as well as the desperation and determination X and Zero feel in relation to finally fighting Sigma after a long rebellion. It works on both a mechanical and on a narrative level.
As you make your way through his fortress, you see Zero facing off against Vile, that invincible bastard from the intro stage. The two of them run off ahead of you, and you can only hear the sounds of battle as they fight one another, the vicious clanking of metal and the blast of energy cannons, culminating in the sound of a barrier being raised. When you finally arrive on the scene, Zero, who has been played up to be far more powerful than you up until this point, has been captured.
You square off against Vile, and again, you cannot scratch him. It's a total repeat of your scripted failure at the beginning of the game, leaving you hopeless. After being defeated a second time, Zero breaks free of his capsule. His theme song starts to play as he latches on to Vile's ride armor, blowing himself to bits in a last ditch effort to defeat him.
But despite this, Vile survives. X, who has been brought down to minimal health, suddenly breaks free of being immobilized. His life bar fills back up to maximum. Vile is in awe, wondering where X's newfound strength comes from. X doesn't say a word, but you know - he just saw his mentor die, by the hand of the same man who's made X fully aware of his weakness twice now. And the man who caused his death is still alive. You fight Vile, and are finally able to defeat him. After the battle, you run to Zero's side and are treated to a death scene, where Zero passes on the job of stopping Sigma's rebellion over to you. If you haven't received the X-buster upgrade, he even gives you his own buster.
This is the perfect "full circle" moment - you, X, started off as the weak underling who couldn't match his mentor's strength. X was full of self doubt. X couldn't even touch Vile. Now, after becoming much stronger, he has defeated Vile, taken the place of his mentor, and is ready to enter the fight as Sigma's number one threat. This is his defining moment; the moment where he overcomes all of his weaknesses and steps up to be the person he wanted to be from the beginning. Again, it's the seamless marriage of gameplay mechanics with the narrative being told that makes this so effective. The player is essentially X, and, unlike a movie or a book, has the added notion of having overcome their own failure as well as the character standing in for them.
The bosses in Sigma's fortress are menacing and inhuman, which really drives home the fact that you're in dangerous territory. Up until now, you've been fighting themed animals. Electric monkies, frosty penguins, flaming mammoths, you name it. None of them would seem out of place in a Ninja Turtles cartoon. But here, you fight cold, unfeeling, sinister looking machines, enemies more akin to something out of a darker sci-fi movie. It should also be noted that the bosses throughout the rest of the game have weaknesses that allow them to be easily beaten. While some of these fortress bosses also have weaknesses, none of them can be "cheesed" the same way as the others, making them much more inherently challenging. Let's take a look at them all.
Rangda Bangda, a gigantic, imposing face in the wall with both ends of the room constantly closing in on you and threatening you with instant doom:
Bospider, a gargantuan spider that comes at X with lightning fast reflexes and spawns miniature versions of itself to attack him:
D-rex, a dinosaur themed tank with a levitating face that violently crashes around the room and crushes X between its upper and lower halves:
As if these weren't enough, you have to face all eight mavericks again throughout the fortress. And they aren't placed in an arbitrary capsule room, either, as they are in other Mega Man games - they'll attack you intermittently, often without warning. They'll drop from the ceiling and ambush you outside. Sigma is pulling out all the stops to defeat you at this point, and it shows.
Then you reach the final stage. It's a long, vertical shaft leading up to Sigma's "throne". The room is dark, and you can barely see. Sigma remarks that he was expecting Zero, not you. This has a double meaning - first, he's reminding you that your friend is dead, taunting you in your moment of supposed triumph. Second, this exemplifies the fact, again, that X has finally caught up to Zero in terms of strength.
Sigma sics his dog on you, not finding you worthy of his time or attention. You dispatch him.
Sigma decides to fight you himself, and you take him down.
The room lights up, revealing a massive wolf construct. Sigma's disembodied head eerily floats from the ground, lodging itself in the head of this gigantic robot beast.
There's no hard rock, heavy metal esque music for this battle, no sir - a sweeping, almost orchestral track plays as you ready yourself for the most challenging enemy in the game. After finally taking him down, the fortress begins to explode. X teleports out and watches it fall into the ocean from the distance.
That music gives me the chills every time. It says more than any of the text does. It says: "Victory has come, but at what cost?"
God, the end of this game is so good.