Oh wow. Mega Man Legacy Collection is really just an overglorified emulator even when they claimed it wasn't. I actually considered buying it, but now I'm convinced it's a ripoff.
Reddit Hacker 1 wrote:
Stored inside the .exe of the Steam release of the game, ROM files can be found for the six Mega Man games. [this part is redacted due to going into detail about disassembling the files, which I'm pretty sure is covered under the ROM hacking rules] Once this is done, the game can be played on any NES emulator like a normal ROM file.
It's basically all six ROMs with only one change: "Licensed by Nintendo" being removed. All the extra stuff like the art and challenges is stored in a zip with a password.
Reddit Hacker 2 wrote:
After digging around the engine in a disassembler, yup, there's a NES emulator in here. (The classes that "hold" the games are even called bs::nes::MegaMan which implements a bs::nes::NESSystem class too

)
I will give them one thing: it doesn't just straight-up play the ROMs, it just pulls all the resources from them and feeds them into the "Eclipse Engine". However, you can throw some ROMhacks in there and the game works just fine.
Prof9 on Twitter wrote:
I threw in a simple Mega Man 2 ROM hack, and it seemed to work fine. Other hacks like MM3 Enemy Lifebar didn't work.
Regarding MMLC embedded ROMs, I also tried to chuck in Japanese versions and other games using the same mapper. They all crashed the game.
If they just wanted to emulate the games through their own stupid engine, they shouldn't have even bothered at all. This is such a blatant cashgrab.