To blow off some insomnia steam, here's an idea I thought of for a game.
Alucard's backstory fleshed out. The intro would begin with the murder of Lisa. Kid Alucard (heh) watches her mom die. Flash to a gloomy, huge mansion after this. Dead silence. Mathias sits perfectly still, reading. One of his most trusted allies, accompanied by his human bodyguards, comes in. He kneels. Mathias turns around to face him.
Closeup to the dude. He has a worried look on his face as he begins to break the news. "My lord..".
Back to little Al, running teary-eyed. Unknown to him, he is chased by vampire hunters. Back to Mathias. He puts his hands on his face, his eyes turn red and he lets out a surge of energy as he roars sorrowfully. The energy immolates the bodyguards.
Back to Al. He sees his chasers, stumbles and tries to hide from them. But they find him and as they are about to stake him, papa Drac shows up and brutally tears every hunter to pieces. After the massacre, he goes to Al, kneels, hugs him and puts his hands on his shoulders.
"Do you see the true monsters before you, Adrian? Those who plague this world? It is that same disease that took your mother from us."
Al sobs. Drac continues.
"But we are strong. And it is the strong who remake the world".
Al's face is filled with rage.
"I want them dead, father! The animals that did this!"
"We will get them. And we will rule all of them and then crush them. Together, as father and son".
Cue credits, accompanied by artwork that depicts Drac training Al, commanding a horde of vampires and both of them committing atrocities against the humans.
The game would begin as Drac leaves the country to prepare for the upcoming war. This leaves Al in charge of the "operation". Initially, Alucard would be murderous and vile, prowling the night with his father's minions. But Lisa's words would echo in his head and he would eventually turn into a Batman-sort of vigilante who starts to right wrongs in
secret from his father's allies. Initially, the enemies would be rival vampires, demons and vampire hunters. This is how Alucard would meet Sonia, a young vampire huntress and, at least in this timeline, the sister of Trevor Belmont.
The game would let you explore villages/cities from the rooftops to the streets, using vampiric abilities. You could do all sorts of sidequests or just sandbox the time away. The main conflict woul be between an order of corrupt humans and demonic creatures that want to take over Drac's domain while he's away. Alucard intially fights them because his loyalty to his father remains in some form until the end of the game, but also because unlike the vengeful Drac, their motivation is simply power. So, he upgrades himself throughout the game and uses an early version of The Castle, to fight the order.
In case it would make people go: "this is so un-CV and it goes against the canon", I would accept using the title of Demon Castle Gaiden etc.