The ESRB has just given a teen rating to Castlevania the Adventure: Rebirth for WiiWare. It is apparently a remake of Castlevania the Adventure for the original Game Boy handheld. The subtitle of the game means it's in the same family as the Contra and Gradius Rebirth games. Below is the ESRB listing.

Castlevania the Adventure ReBirth
Platform: Wii
Rating: Teen
Content descriptors: Animated Blood, Fantasy Violence

Rating summary: 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.