To celebrate both Mega Man and Street Fighter's 25th anniversaries, Capcom has partnered with Seo Zong Hui to release fan game http://www.capcom-unity.com/mega_man as a free PC download.

Eight stages and eight new power-ups as you would expect from a traditional Mega Man game, but with Street Fighter characters as bosses. Level design and mechanics deviate a bit from the norm to accomodate Street Fighter influence, but it's still Mega Man through and through. They're also using this to gauge interest for the Mega Man franchise moving forward, so if you're a fan then at least give it a try.