The boss selected music is from Atlantis no Nazo.
The boss defeated music is from Pokemon.
I actually can't recognize any of the regular level music myself.
Also, someone forgot to tell the author actual vertical scrolling isn't allowed in the NES Mega Man games.
I had just beaten my first boss. Drill Man can be a little pesky, but his attacks are pretty easy to dodge. Watch out, though! He does this one move during a pinch, when a column starts shaking, he's going to sucker punch you with an auto-kill move if you don't move ASAP. That one move makes the fight a nerve-wrecker.
Alright, after beating him, I heard the obvious Pokemon jingle, and then the weapon get music started playing. And when I heard it, I was like "NO ****ING WAY! REALLY?" The song I heard was the dungeon theme from RPG Maker for the Game Boy. But do you want to know the "NO ****ING WAY! REALLY?" part? ...This isn't the first Megaman hack to use that melody. It was also used as the Stage Select theme for Rockman Unprecedented. I mean, seriously? Such an obscure game for not one, but TWO Megaman Hacks to take the SAME SONG from.
Edit: I've been flying through this game so far. Free guys seem to come more often, especially with the Rush Search. And it's nice that weapons fill up a bit after you die. Honestly, this game, so far, has blown me away! It's simply amazing! There's so many tricks and puzzles, the game is jam packed with new ideas and references. There's even a boss in Ringman's stage that is similar to fighting Lololo and Lalala from Kirby, except with one more guy. And these bosses have such interesting strategies, like Brightman's attack where he throws a lightbulb into the air, and you have to stand in Brightman's shadow or suffer serious damage. ...But I do kind of dislike how some of the bosses aren't so much strategy, but bosses like Ringman and Pharaohman throw so much stuff at you it's impossible to dodge, pretty much turning the fights into "Kill him before he kills you," matches: a name given to boss-fights where damage is pretty much inevitable. But still, with the right weapon and maybe a few energy tanks, you shouldn't have much problem killing them first. I also think the game could have benefited from a better soundtrack. So much obscure music, not enough recognizable music, plus the music isn't the best quality. Still I suppose hearing the F-Zero Silence theme is cool.
Other than that, this hack is as good as the description says. And it's nice that it isn't too difficult as well. They give you plenty of help along the way.