Undertale is an amazing game. I really enjoyed my time playing it. I listen to the sound track a lot(I'm doing it as I write this). I even read a fan-made AU called Inverted Fate. The only thing that I haven't done(and don't intend on doing) is a Genocide Run. But, there's one thing that's kinda been bugging me since it first found out about it. It's the fact that their's a version of Undertale(the song) that wasn't added, and instead was replaced with the version we have now.
The Current Version
The version we got of Undertale was a pretty good one. It's a little sad, while also filled with hope(just like the monsters in the neutral route. It is kinda the song of their hope, since it only plays during the end of the neutral route). Below is the version we got in the game.
The One that could have been
This one is also great, and I personally think I like it a lot better than the one we have. I feel like it's more happy in tone. Even if it might not fit with what the game would have been trying to fit it's context into, it's still a good song on it's own.