Everyone's heard of rock/paper/scissors, and since Bitcoin uses cryptographic hashes to make it secure, why can't rock/paper/scissors?
So, here's what you do: Choose rock, paper, or scissors, and hash that , underscore, and 20 random capital letters, with sha256. For example, if you were choosing paper, you could hash "paper_WJJADWEQJGOSOTHIURXX", and get df9c9320c577fff3cfe35beb8e139a7ecb4d7fd155a48118f28d30e254128295.
Post your hash, wait for someone else to reply with their hash, then both people provide their original strings, revealing the winner. Sound fun?
You can use the random string generator here to get the 20 characters:
random.org/stringsChoose 1 string, 20 characters, only uppercase letters.
I'll start with bb42b7b6f3522e643ba2880c986f8d7b4098a302a832e52a8d1e327071b3158f