There have been many Mega Man hacks over the years, and this might be one of the stranger ones. Or maybe not, it's hard to tell.
In any case, this one seems to place you in the role of a greyscale version of Copy Mega Man, fighting against the robots of Dr. Light. Check it out:
The "CX" in the title is presumably a reference to the Japanese video game show Game Center CX, given the various bosses from other games featured within, including Fire Mario, Whispy Woods, and of course, Mega Man himself.
The game is also much faster-paced than the original Mega Man titles on the Nintendo Entertainment System, featuring speedier enemies as well as dashing and a machine gun-like Buster to compensate. Getting to play as Quick Man seems to help further punctuate this, and using his Quick Boomerangs the way he did in the original game looks extra-fun as well.
Here is the link to the ROM, though you'll still need an NES emulator to play it.
Thanks to Dega Vega for the tip!