Mega Man 2.5D is a fan game developed by a small team of obsessive Mega Man fans. It began in 2009 as an animated proof-of-concept. The concept got a surprising amount of positive feedback, and because of this we got a bunch of people together with the goal of making a playable game out of it.
There are mainly two things that set the game apart from most other Mega Man games. The first is the co-op mode, where two players team up to take on the robot masters. The other is the use of camera perspective changes which is featured a lot in the single-player mode of the game. The finished game that is due for release at the end of 2015 will also contain a VS-mode where the players can battle each other, or complete in a point chase.
We ran into a lot of problems during the early days of development, and because of this the development pretty much stopped at one point. Fortunately we were able to get it back on track in mid 2012, and since then things have gone much smoother. We're now on track to have the game fully finished around december of 2015.
Feel free to check out some videos of Mega Man 2.5D here.