Billy: The RPG is a fan-written homebrew roleplaying game set in the Billy Vs. Snakeman MMORPG. From the game's opening:
"The Billy vs Snakeman world is set on a fictional world resembling Earth. Ninja’s live and die under the rules of a village. There are many villages and all have different cultures and customs. There are a myriad of medieval weapons sharpened and shined, ready to bring down absolutely anything that tries to get into the villages, so it should be fairly safe on the inside. It’s the folks in the Countryside that have to worry about enemy ninjas during times of war. Soul Reapers are probably few and far in-between, Patrolling in small nomadic groups, or in small settlements of their own. There are non-Ninja gangs who actually relish in the countryside, with only the strongest on top, and no law enforcement to hold them back. In any case, they must practice constant vigilance, or become vittles for the next murderous pack of Ninja that they come across.
"Characters in Billy Vs Snakeman are meant to kick ass and take names, and with all that Ninja booty roaming around they can keep occupied for quite some time. It’s up to your Gamemaster (GM) whether they want to run a Dipomatic campaign or a brawler, but I feel that one of the series best draws is the crazy-awesome Humor, Bringing down dozens of Insane Idea’s at the same time and generally amusing everyone: Focus will be on being inventing and humorous. Mad fighting skills help, though."