Fan-made boss fight: "Unknown"

Now, for anyone who's played Undertale, we all know that there is a lot of time travel shenanigans with the SAVE feature, but what if there was someone, or something, that wasn't too happy with you wreaking the timeline? Try it out for yourself: https://www.dropbox.com/s/60e26gri7y9nx42/Unknown.zip?dl=0 Also please post your comments here on ways to improve this, I know it isn't perfect and I would love to fix it, thanks.

Oh, and I almost forgot, music credit goes to this guy: NPC - https://www.youtube.com/user/nonplayablerecordsAwesome song dude.