hey Hive account@pinkfloyd878,
you're right that trx IDs are "completely random and unpredictable", but are you aware that they are known after signing the transaction and before broadcasting it to the blockchain?
That means that the score can be known before sending a transfer to Hive account@hashscore.fun, and users can tune their transaction to match the target score. (see my last two rounds for an example...)
Kudos for what you built, but you should definitely rethink your algorithm!