This Comic's Storylines:

And, quickly and without any pomp and circumstance, we enter into the next "game": Castlevania Gaiden.
I have a few things to point out about Gaiden, the first of which is that the title is kind of a misnomer, really. A gaiden (in the Japanese) is used to refer to a side-story, one that isn't really a sequel or prequel, and often just retells a previous story from a different perspective.
In a sense the title works, but only if you know the backstory for this adventure. The original intent was to have Castlevania Gaiden be a game (the details of which can be found in the Abandoned Stories archive). The game was going to follow Darkmoon (and/or Alec, depending on the character you were using) as they went to defeat Dracula (who had taken all the barmaids). The comic was intended to be a supplement to the game so that those who couldn't play through it (since it wasn't going to be super easy) could still read the story, although enough changes would be made to the two versions of the adventure that ideally you'd want to play the game AND read the comic about it. Thus, a gaiden tale.
Unfortunately, the guy that was working on the engine for the game fell off the face of the planet (as so often happens with homebrew games), and Gaiden languished before just disappearing for my plans.
Interestingly, there was a demo of the final battle with Dracula that he made, which spawned the whole idea. Sadly, that was lost in a computer reformat, and I don't know if I'll ever see it again.
Anyway, as far as official continuity, the way to think of this is as a direct sequel to CVRPG II without it being a whole new game. In game parlance, this would be like an expansion pack (or DLC) for CVRPG II. Another way to look at it is by the Final Fantasy game logic. CVRPG II then spawned CVRPG II-2 (much like Final Fantasy X and Final Fantasy X-2).
Regardless, on with the adventure!
 
    

When evil spreads across the land, and darkness rises and the monsters roam. When the creatures of the night make beautiful music, and the things that go bump in the night go bump with greater enthusiasm. When the world is in peril and is in need of a hero...

These guys are, sadly, the best the world can hope for. These are the adventures of the heroes of CVRPG. They mean well, they try hard, and occasionally they do the impossible...

They actually do something heroic.