Every now and then you'll have a huge fan of Castlevania come out of the wood works to show off some of their fan based handy work. Such is the case with "CastleMania", which is a short but great game based on the NES 8-bit days many of us grew up with. While paying homage to the long time running vampire hunting series, CM uses many elements from the first hit title that made it so great. If you want to play it, you will simply need to install the "Unity Web Player" to play this short but tough game. You can get it at the official page here. It was recently featured on NESJAM and was created by Zombiesaurus Games.
While this is but one title in the works, there are many others out there that take inspiration from Castlevania, and even are meant to be part of the story line if you know which ones to get. A quick Google search should land you where you need to go.