For a few hours, Undertale is a solid, charming game. Then you get to the ending — the real ending — and suddenly you get why everyone's so obsessed. In fact, I'd argue that Undertale's true final boss — which you can only see by completing the game as a pacifist — is on par with the best finales in RPG history, rivaling games like Earthbound and Chrono Trigger in sheer gut-wrenching poignancy. Undertale might also have the best boss music of any video game to date. (Don't listen to it until you've fought said boss, though.)
If you've finished Undertale but haven't gotten the true ending, you haven't really finished Undertale. The good news is that it's not hard to get: Just complete the game without killing anyone and make sure to befriend every major character. If you're level 1 at the end, you're golden. Go finish the game and then wander around until you get a phone call. Follow the directions from there.
If you have seen the true ending, let's talk about it.
SPOILER WARNING: DON'T SCROLL PAST THE DOG IF YOU HAVEN'T FINISHED UNDERTALE.
Let's set the stage. Asriel, the misguided demon prince who has been following and hounding your character for the whole damn game, has absorbed your friends' souls and emerged from flower form just in time to play with you.
"It's me," he says. "Your best friend."
This is something of a shocker: You'd heard of Asriel, the child of Asgore and Toriel, but who would have thought he was actually Flowey the whole time? The first character you meet in the game, the one who tries to convince you that the mantra of Undertale's world really is "kill or be killed"? That was Asriel all along? It's a good thing you never listened, or else you wouldn't be here.
Anyway, Asriel's here to fight you. And he brought along one hell of a theme song.
At first this feels like any other fight, one you can win by outlasting your opponent and saying the right things. But you'll soon realise that your only interaction options are "Hope" and "Dream" — certainly not enough to convince this demon child to go away.
As Asriel starts firing attacks at you, whipping out shooting stars and energy beams in an attempt to blast you to oblivion, he'll explain that he just wants things to go back to how they used to be. He wants to hit the reset button and go back to before. Before that first human ruined everything. Before an interloper named Frisk started trying to save the world.
At some point during this barrage of bullets, you might lose all your HP. You'll start to see the standard Game Over screen. Then this will happen...
You can't die, of course. You just can't. You're too determined.
After a couple dozen rounds with Asriel, he'll start to realise that he can't destroy you. He'll say you've only seen a fraction of his true power — classic RPG boss, am I right? — and then he'll grow technicolor wings. The music will swell once again.
You don't have many options at this point. Your health is low but you can't use healing items. You can't fight or spare or even try to run away. Your only command option is "Struggle", which is more than a little disconcerting. You begin to worry that you did something wrong and that you'll have to start again.
At this point it becomes clear that, if you're going to win, you're going to have to do something drastic. Earlier, you'd learned that you the player can manipulate events in the world of Undertale through save-files, so that's what you'll try to do. But Asriel stops you. By absorbing all of those souls, he's gained the ability to block your powers.
"Seems SAVING the game really is impossible," Undertale tells you. "But... Maybe, with what little power you have... You can SAVE something else."
That's when you figure it out. You're going to have to save your friends.
There are six major "friends" in Undertale, and up until this battle, I hadn't cared too much about any of them. I found Papyrus's brash stupidity to be annoying, not charming. I thought Asgore was a big dumb doofus and I just couldn't stand Alphys and her nerdery. (Undyne can do so much better.)
Then this fight happened.
As the music swells up and down, you'll gradually save each friend, dodging their old attacks and bringing them back from the abyss by reminding them of the memories you've shared. Crosswords! Spaghetti! Butterscotch pie! It's an incredible few minutes, enhanced by the stakes, the music, and, for me, the sudden realisation that these characters are actually kinda cool. Yeah, even Alphys.
Once you've rescued your friends, you'll realise that you have one more soul to save. And if you're not already bawling as you mash the SAVE button over and over again during the final part of this fight, well... You will.
The whole sequence is spectacular — the payoff of this battle justifies even the slowest of Undertale's setups. And the music. Dear lord, the music! Over the weekend I listened to the final boss theme while doing dishes and it was wonderful. Felt like I was saving those plates' souls.
For a long time I was sceptical that Undertale could live up to the hype, and even as I played through the game — on New Year's Eve of all days — I didn't buy into the breathless adoration. Then I fought Asriel. It's hard to imagine a better ending to 2015.