The Raindrops Protocol is a series of five a la carte contracts that govern on-chain or proof-on-chain data specifically for games, allowing any player or item to be interchangeable with any game client that can process them. The Solana ecosystem has a fragmented and very customized way of storing in-game assets on-chain, with many different formats. But the Metaplex Protocol's methods of storing ordinary NFT data are standardized. The aim of Raindrops is to do the same thing for game assets.