One of my favorite doujin groups is Dangerous Mezashi Cat. They have many different members and have published 8 albums so far. Doujin groups are quite different from the people that normally arrange video game music albums, as they are not actually hired by the company that made the game. "Doujin" essentially refers to a fan-made thing, or a group of people that share an interest in something. This is not to be confused with an amateur status; the doujin groups do sell their albums and make money. They just aren't officially recognized. However, since they are simply fans, the quality ranges from phenomenal to atrocious. Many thousands of doujin albums have been released in Japan, alongside the many thousands of official albums.
Here is what the artwork looks like from Dangerous Mezashi Cat's latest album:
As you can see, they even went through the trouble of making a picture disc, which I think is really cool. On this album, they arrange music from the earliest Megaten games, which is short for Megami Tensei, a popular series of games in Japan. The music is similar to Castlevania, mainly because of the gothic sounds. Even though I've never played any of the Megaten games, I am quite familiar with the music, as I've listened to almost all of the soundtracks in that series. Thus, I found this CD remarkably interesting for the new arrangements of music I have loved for many years.
One thing is very much for certain - DMC is getting better. There is absolutely no way for a casual listener to single this music out as coming from a video game.
This CD was released on Dec. 30th, 2009 and I received it just a few days ago. It's important to buy these types of CDs right when they come out because the print runs are very limited, which can potentially skyrocket the price if it becomes popular. It is very easy for these albums to reach $50 and then $150, so if you wait, you're either going to pay out the ass or have to find someone willing to trade. Or hope someone posts it on the internet.