For a bit more elaboration: This game is apparently a remake of the creator's first ever fan-game, released way back in 2003. The remade version of the game offers way more content to it, having 4 playable characters: Mega Man, Proto Man, Bass (apparently a fake/copy version of him, hence his rather sub-par design in-game. Don't ask), and Slash Woman (again, don't ask). Of these characters, Mega and Proto are the only ones remotely finished in the current demo. This is where the gameplay also starts to diverge heavily from the traditional series, most of it for the worst. On the other hand, I can almost guarantee that some of the things I'm about to say are going to make you want to play it.
For starters, Mega Man has nearly every single weapon from almost every single classic game available from the start. This even includes the Mega Man Killer weapons from the Game Boy ones (yes, even the Sakugarne). The only things he doesn't have are the various support weapons (Item 1, Carry, etc), the Dimensions' weapons from the WonderSwan game, and the weapons from 9 and 10. He can equip 2 weapons at the same time and use them with separate button presses. Adding even more onto his ridiculous arsenal are the weapons you get from the "original" Robot Masters in the game, along with the ability to call out Rush, Beat, or Tango as support that follow you around. Each one also has their own Super Adapter form as well, granting unique abilities in the process (though Rush has a different one compared to 6 and 7's adapter's).
Honestly, there's quite a bit of effort put into this game. There's a boat-load of custom content, especially in the graphics department, even though it doesn't follow the traditional 8-bit format. Then again, I'm not one to get picky about that sort of thing unless it becomes way too distracting (but we'll get to that in a moment). However, good effort does not make for a good game unless applied properly. Some of the game's ideas are really cool, but that's sadly about all the good I can say on it.
Now it's time to move on to the bad: As you might be able to tell, this game is a victim of its own ambitions. So much content has been shoved into this that it definitely feels like it's aiming more for quantity and flashy substance rather than quality control. Even though Mega Man has access to almost all of the Robot Master weapons, I can tell you straight forward that you'll only ever need 2 of them: Top Spin, and Thunder Beam. The reason for this is that every enemy in the game (including bosses) lack any form of invincibility frames. As such, weapons with sprites that pass through and/or linger inside enemies are far more effective than those that don't. Using the Thunder Beam at near point-blank range is almost a guaranteed instant kill on almost any minor enemy, mainly considering its base damage output (which is already very high) gets multiplied while the projectiles lag inside the enemy's sprites. Meanwhile, the Top Spin has actually gotten a significant upgrade from its original counterpart, where you can now spin indefinitely so long as you hold down the button and still have energy left. You can even move around during it and use it on the ground as well. This means you can literally spin through almost the entire game like some kind of deranged lunatic, tearing both enemies and bosses apart with little to no effort.
Aside from most of Mega Man's weapons being made useless thanks to "Top-Spin-Master-Race," the rest of the gameplay also suffers from general coding as well. Everything feels insanely loose and slippery with this game. Couple this with level design that feels more like playing a bad ZX Spectrum game than a Mega Man one, a ton of unnecessary extra bits (skill-trees, a level up system, etc), and it all starts to devolve into a gigantic, tangled mess. That's all without even going into the bosses either, both the Robot Masters (which there are 20+ of them) and the Fortress Bosses that the creator has shown off so far.
I'll admit, I got a kick out of Pro Action Football Man (no pun intended, even though the actual kick move he has does an absurd amount of damage), but a good portion of them are downright uninspired. Shark Man (not the one from MMDOS) is literally just a Sharkticon from the Transformers series. It's not like Maelstormm is doing anything to hide this, either. His stage is actually modeled after the area where the Sharkticons appear in the 5th Transformers movie, and even plays the song heard in that part in the movie (Nothing's Gonna Stand in Our Way by Spectre General). Even more-so, Shark Man himself turns into a more humanoid form for one of his attacks, complete with the trademark "transform" noise from the aforementioned series and a Decepticon logo on his chest. Some of the other bosses (particularly the ones on the bottom row) are also lifted from other sources. Stealth Man is Snake from the Metal Gear series, Strider Man is basically Strider Hiryu himself, and Psycho Man is Jason Voorhees with random gobbledygook pasted onto him. There's taking inspiration from something, and then there's just outright copying.
The Fortress Bosses aren't that much better either, although this is mostly due to immense amounts of "WTF?" decision-making coupled with the usual lifting from other sources. To put this into perspective: The first Wily Fortress boss is apparently Rydia and Leviathan (http://www.youtube.com/watch?v=U9WGlMAn-Vw) from Final Fantasy. Why? Your guess is as good as mine. Have you ever wanted to fight Utsuho Reiuji in a forced Rush Jet segment (http://www.youtube.com/watch?v=jbVRFgJphFE) in one of these games? Even if you're a die-hard Touhou fan, I'm guessing probably not. This game also sports a Devil Boss (http://www.youtube.com/watch?v=igtP9qoFDvU) that makes the Black Devil from MMX5 look fun by comparison, along with Gamma after he auditioned to be the final boss in the next Resident Evil game (http://www.youtube.com/watch?v=3cbyhmZJlIM). Oh, and War from TMNT Tournament Fighters (http://www.youtube.com/watch?v=02KAHaBtU6I) is also a boss in this game. Why? Because reasons. That's why. You also get to fight against Roll as well, in the same vain of her being reprogrammed by Dr. Wily in another (better) fan-game. Only here, she looks like a glob of playdough and is apparently possessed by Satan (http://www.youtube.com/watch?v=tXheQlTVV3A).
The final two bosses seem to have their own unique problems as well (although I do admit, I kind of like the design of the pre-final boss, despite not really fitting with the Mega Man style). The first one, if I can borrow a quote from Yahtzee - "is fought on top of a stupid sci-fi tower that looks like something the Combine would throw together if they were all drunk." The final boss however, is fought on a forced Rush Jet segment, in which it basically seems to play out like every bad shmup ever. Both of these bosses have instant kill moves as well. Jaguar, the pre-final boss, can execute this by simply coming into contact with you when his health is low enough (http://www.youtube.com/watch?v=tG1yMMxSJiM). The final boss however, has a gigantic instant-kill wave that covers 95% of the screen, and can apparently be spammed continuously (http://www.youtube.com/watch?v=i81juyh8Z_E).
When it comes down to it, I'm starting to get the feeling that this shouldn't be considered a Mega Man game. Sure, it has Mega Man as a primary focus, but there's so many cross-overs/lifted ideas and other nonsensical features sprinkled in that it starts to feel more like a bad, playable fan-fic than a Mega Man game.