You’ve got to love ratings board lists!  The ESRB has listed an entry for Castlevania: The Adventure ReBirth, and it has given the game a rating o T for Teen.

The ESRB describes the content as “This is a side-scrolling action game in which players battle against monsters in Dracula's castle. Players use a chained whip to fight their way through halls and dungeons filled with zombies, skeletons, flying eyeballs, and bats. The enemy creatures frequently shoot projectiles and attack players in hand-to-hand combat. If players sustain too much damage, they keel over and emit a burst of red blood. Some rooms in the castle also have spikes or spears stained with red, blood-like splotches."

According to Wikipedia, Castlevania: The Adventure was a little-known Game Boy title originally released in 1989. It was subsequently rereleased in December of 1999 for the GameBoy Color in European territories. 

Castlevania: The Adventure ReBirth will be the third classic Konami franchise to carry the ReBirth moniker, with Gradius and Contra being the first two, respectively. No release date or specific platform has been detailed as of yet, but considering the other two series hit WiiWare, we’re assuming it will be a Nintendo exclusive.