It's got that feel like... "You've come a long, long way to get here. This is it, the bitter end you've been clawing your way towards. You wanted to be here, but you don't want to do this. Hell... -I- don't want to do this. But we're past that now, no turning back. It's time, kid."
I like the idea that megalovania isn't actually Sans's theme, but instead Frisk/Chara's theme. There is a song with a name that states it would play when you fought Sans. Also, at the end of the geno route, it's more like Frisk is the monstrous end boss and Sans is doing a one-sided fight against her
Fighting Asgore my first playthrough (neutral, no kills), hearing his theme almost had me in tears. Definitely the best song in the game, in my opinion.
If he does, can you blame him? Everything's going great in his life trapped underground, then one day both of his sons die, his wife abandons him and runs off for years without him knowing if she's still alive, and he's still shouldering the burdens of an entire kingdom lost in despair, while also bearing the sin of having to kill any human children who wander down into his land, which he does NOT want to do, but apparently won't let anyone else have to live with that pain.
All this for a promise he made when he was too angry to think straight. Because if he does lead them all back up top it just starts another war with humans - and just being ANGRY at a monster can hurt them. Humans are little BUT anger and xenophobia.
I wonder what software Toby used to make the music for Undertale, I read somewhere that he created the music before the characters or the fights or something like that