I'm not sure a game needs transactions. It seems to me that entity streaming concepts are a better fit: reading from an event queue and consistently reconciling the state over time. Like the sorted top-n in the example, if it was a game and the query is generally known, it would be better to just materialize it as a fast rank, which goes beyond the IVM-style materialization they suggested.
Eeeeeh. You can never trust the client, but the server is far away, so most games have speculative execution of actions and then the server can tell them to fuck off and revert/ignore the action.
