WMG / Boktai

The Doomsday World is a fusion of all worlds that have ended or are about to.

The End of the World isn't just a time, it's a place. The Valley of Megiddo. The part of the multiverse that's circling the drain. Thus, any world that ends fuses with it, with the Zombie Apocalypse waiting for them. This is why Bok Zombies can respawn, defeat one, and eventually a timeline where it wasn't killed manifests. This also means that worlds that are in critical danger of ending have a very thin dimensional wall, hence the worlds of Mega Man Battle Network and Metal Gear have had incursions.

• This also explains Vamp.

• For a brief period of time, The Heartless of Xehanort from Kingdom Hearts made his base here. "The End of the World" after all.
• Also, the entirety of Hellgate: London takes place there with the human "survivors" still battling the demonic and undead hordes out of a mistaken belief that their world still exists and can be saved.
• The abyss from From The Abyss is either the Doomsday World itself, or a tunnel leading to the Doomsday World.

Dark Matter is a form of Nanomachines

Oh, there's a lot of psychic/spiritual energy involved, but ultimately the Immortals are just the remnants of Neglectful Precursors who believe their own mythology. It's latched onto Dark Energy as its power source, which is why Sunlight can destroy it.

• As Metal Gear Solid 4: Guns of the Patriots shows us, nanotech can do a lot.

The world of Boktai is the aftermath of the apocalypse in the Mega Man Universe

This would explain the Schizo Tech. An advanced solar-powered gun, connections to Battle Network's net, a bank with computer terminals, and a huge and apparently quite complex clocktower all exist in an apparently medieval setting?

Galaxy Universe/The Will of the Galaxy was formed from remnants of Sailor Galaxia's Chaos-afflicted energies.

• Her compassion was twisted by the energies of Chaos: in an attempt to free the Universe from Death, it became Klorofolun, which causes Undeath.

The vampires in Lunar Knights are a degenerated breed.

And immortals are still the same.

After Ratosk was slain the stock of immortals suffered as a result. Next line of vampires was weaker as a result, lacking the fabulous powers of their progenitors. In order to even hold a candle to them, the vampires had to not only infuse themselves with the power of the earth itself (the terrenials) but also build advanced armours and machines to back them up. the immortals decided that they could afford to let the vampires run amok on earth in their stead as their reliance on their supernatural and technological crutches would make them easy to overthrow if they became a problem. Hell even two kids with a sword and gun between them absolutely wrecked the vampires in a matter of days.

Duke Dumas and The Count are the same person.

Both Dumas and The Count exhibit similar traits, particularly their prominent horns and their power to transform into a cloud of bats. Both are also displayed as being disdainful of Ratatosk, with The Count working to backstab him in Boktai 3 while Dumas outright kills him at some point prior to Lunar Knights. Prior to his battle with Lucian and Aaron, Dumas also seems to be particularly excited at the prospect of having a proper battle for the first time in a while, even beginning to use Aaron's name for the first time as a sign of respect as opposed to before when he simply referred to him as "boy".

As for his different appearance, that could be chalked up to him completing his goal in Boktai 2: stealing ShadeMan's body. Dumas is notably as slim as ShadeMan and has similar wings. And while he was seemingly killed off in Battle Network 5, it's also established that he and the other Darkloids can revive so long as darkness exists. Dark Chips still exist in Battle Network 6, albeit in a limited capacity, so it's possible some remnant of ShadeMan could still exist. Finally, The Count is shown to appear in Battle Network 6 sometime after Boktai 3, given that Django uses equipment from later in Boktai 3, like his Coffin Bike and the Solar Trap.

Based on that, given that Django dies in the Lunar Knights timeline, it's possible that The Count would have been able to go about invading the Cyberworld without any interference from anyone. While there, he was able to discover some sliver of ShadeMan, assimilate it to change himself into what would become known as Dumas, and then return to his world with a greater amount of power.

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