Castlevania: Grimoire of Souls
After the events of Castlevania: Dawn of Sorrow, Alucard (continuing to operate under the guise of Genya Arikado) continues his work to prevent the rise of Dracula's power once more. Receiving a letter addressed to him (under his real name) from a Lucy Westenra of the Elgos Order, Alucard goes to meet the woman to discuss grimoires, books of dark and evil power that could, potentially, be used to resurrect the Dark Prince.
During the meeting, Lucy reveals the full extent of the power of the grimoires: they can actually suck people into them, transporting them to a very real looking, but still supposedly artificial, version of history. In essence, the books allow the uses to travel backwards in time, but it's like being in a pocket dimension -- the actions have consequences, but their actions on affect the book and not actual history... or so the order thinks. But as Alucard travels through the books, seeking to seal away their power and stop Death (who has also discovered the power of the tomes) and other minions of Dracula from claiming the power for their dark ruler, the books might just affect history after all.
The first of the tomes drops Alucard on the edge of Dracula's Castle in the time of Simon Belmont (circa 1691 AD). There Alucard comes face to face with Death but, because the book has stolen away Alucard's power, reverting him to a form closer in power to this time and place, Death is handily able to defeat him. After taunting the hero, Death flies off to secure the power of the book. Lucy pulls Alucard out and reasons that the only way he could defeat Death (and any other creatures lurking in the books) is if he had help. So she manifests Simon Belmont first, and then Charlotte Aulin and Maria Renard as well, to help flesh out the party and give everyone a fighting chance. They then go into the book once more and take on the Giant Bat lurking at the end of the tome, securing the dark soul the Bat was protecting and preventing Death from gaining this power.
Next, Lucy sends the heroes into the era of the evil Brauner (circa 1944 AD. To aid the heroes Lucy summons Shanoa and, at the behest of Charlotte, tries to summon Johnathan Morris. Unfortunately, something has gone wrong with the book, almost like it's actively rewriting itself. It seems that the dark power of the tome is controlling history and actually actively trying to delete heroes, and their adventures, from the timeline (since if the heroes don't complete their quest Dracula doesn't die in that era). Banding together, the heroes fight through Brauner's version of Dracula's Castle (and the dangers within), eventually coming face to face with the wicked Dullahan. A pitched battle ensues that, in the end, leads the heroes to collect their second soul. Johnathan is saved but, due to the changes to history within the tome, he's unable to use his full power and can only assist the other heroes on their quest.
Following this, the heroes venture into the book to the era of Richter Belmont (circa 1792 AD). Here the powers of the book are trying to rewrite history and remove Richter from existence. This also deeply affects Maria, causing her to start fading as well. The united heroes have to venture through this time, to take on the Wyvern at the end of the tome, and steal away it's dark soul as well. This saves the heroes but, as with Johnathan. Richter has been weakened by the corruption in the book and is only able to assist the rest of the team for short periods of time.
The next era the heroes ventured to was actually that of Alucard's own attack on Castle Dracula (circa 1797 AD). Here the heroes venture deep under the castle, through the caverns and cemetery, to take on the dangers within. While in the castle underground they run across a second version of Maria, this time the adult form that Alucard once had a connection, of a sort. The book, though, seeks to delete her, too, and the heroes have to prevent this. Battling through to the undead demon Legion, the heroes take on this new foe for the sake of their friend and companion. The best defeated, the heroes gain the dark soul within, but then Soma Cruz seemingly arrives and attempts to steal the soul from the heroes. A pitched battle ensues, and then Soma retreats, whisked away by a new woman, Hermina. Apparently Hermina was once a member of the Order of Elgos, and she's the one that figured out how to enter the tomes. But then she left the Order and stole several of the grimoires. She may, in fact, be the cause of the corruption.
The heroes at then sent into a tome to deal with the events of the Order of Ecclesia (circa 1810 AD). Here the heroes have to deal with a couple of problems. First, Shanoa begins to fade under the rewriting onslaught of the book. But then, even after battling their way through the barracks of the Castle, the heroes run up against the demon horse Eligor. They have to defeat this beast to secure its soul, but even then that's not the end of their troubles as soon after they save this time, Richter and Maria begin to fade once again and the heroes will have to venture back to 1792 AD to once again see what's going on in that era. But to aid them, Lucy summons Albus, Shanoa's brother-in-arms, to aid in the fight.
...and then the story ends because the game was canceled. However, three more chapters were planned, adventures set in 1792 AD, a return to 1797 AD, and then finally one last quest in 2036 AD to deal with, presumably, Hermina and Soma Cruz (who, we have to assume, was under Hermina's control). Then, probably, a fight with Dracula would have occurred as well since none of these can go without a Dracula fight at some point.
Unlike other stories in the series, Grimoire of Souls doesn't have a single, linear story to it. Instead it functioned (as it was never completed before being canceled.) as kind of Castlevania: Harmony of Despair with a thin layer of story attached. The game was designed for players to go into stages (based on various eras from Castlevania history) and play these areas over and over again, grinding for gear and tokens to get more gear (or, if you wanted to be a scrub, just pay for the tokens to get the good gear). There is a story to the game, as recounted above, but it was thin and served more as a veneer to introduce the various stages.
Also, of course, the story was not finished as the game was canceled. before the last three chapters were introduced. Wherever the story was going, and how it was going to wrap up, is a mystery at this point.
We use the date of 2037 AD for this game as it's ostensibly supposed to happen after the events of events of Castlevania: Dawn of Sorrow, but until an official timeline is released incorporating this game into the series (which, since it was canceled., is doubtful) we'll just have to go with our best guess for placement.