Ask HN: Alternatives to the blockchain when a little double-spending is OK?

Hello,

I'm (trying to) build a decentralized application. I want to distribute resources based on how much a node benefits a network. To do this, I need to track the 'work' done by each node, and allocate resources accordingly.

This needs some sort of immutable database, however absolute correctness isn't required, just mostly correct, i.e. some "double spending" is allowed.

Occasional mis-allocation is OK, because there's no real money involved.

Are there any data structures that can do this? Would a blockchain/tangle with a small POW achieve this goal?