There are a few tweaks in gameplay, but I gotta say, the game design here cannot be saved. So many things I keep asking myself "why is this even a feature, it should just be removed", but the game is already so simple. I think the biggest gameplay improvements are on the stairs and on the boss fight, I made those a lot more playable.
I just found a surprisingly difficult to miss bug: when on the map, if you try to enter a building to the right when there is none (aka when you're on a horizontal street), it will enter the gas station. To the left it will enter a normal building. I think I'll fix this. Strange I never noticed this, maybe it happened and I thought I had pressed a diagonal.
As for music, I have no idea. I guess I'll take a look, and if doable I'll try.
If I did this right, this is a game genie code for moving fast (and just by pressing left or right) on the stairs:
This is of course something the hack comes with built-in.