Nice idea!
agreed.
thought about a game similar to this. however, there would be a
single address and you would join either group A or B based the tx hash (eg over/under 32768 -- for a 16-bit game).
i also thought of a few bonuses that would apply to individuals in the winning group (again all based on tx hash).
what do you think of the name "In It 2 Win It"?
wish i had the time to develop it.
also, considering you have 0 risk, why not lower the fee (say 0.99%) to make it more competitive against sites like SD?
anyway.
good luck