Also, it will feature a Skill Tree System, and kinda like in X6, certain levels will change slightly (in ways such as having new hazards that newly acquired powers can overcome) depending on which bosses you defeat, making the game harder and the order in which you defeat them is more important.
The game will feature these hubs where you can switch characters and armor from in the middle of the stage. X and Zero are both playable, and they will also have the different armor types like in X5 and such. The 8 Maverick Bosses revealed for it are going to be these. He certainly has done an impressive job with the stage design and it could really pass as something in the official series! Not much has been said about how it would tie into the series, but from the looks of things, it is going to be an Interquel of sorts.
It looks very promising from the stuff he's shared so far, and very true to the series. It's not done yet, but he's provided some neat progress screenshots and videos so far. Just a few days ago, I found out about a neat Megaman Fan-Game project in development by someone called John K.