As carltron said, MM vs SF was a fan game. There are actually a decent few fan games that are pretty good. Megaman Unlimited is fun, Megaman 2.5D has a great semi-3d gimmick, and 20XX incorporates roguelite elements and competitive shared seed runs. There's also a megaman FPS game out there, but I've not played it, so I can't recommend for or against it. http://megaphilx.com/?page_id=1003 for megaman unlimited http://petersjostrand.com/ for 2.5D http://store.steampowered.com/app/322110/ for 20XX (I highly recommend this one, competing vs friends in the shared seed challenges is a blast. It ain't free like the other two though)