This video is from a fan made game that Capcom Unity member SonicZH created for a contest on that site. The game pits Mega Man against characters from Capcom's Street Fighter series. The level in this video is neat, but the boss fight with Ryu at the end is what really grabbed my attention.

I love that Ryu has a Revenge Meter that fills up every time he gets hit, just like in Street Fighter 4. Sadly, this game is still in development on, so it's not available to the public yet.