> if there's a Score on the HUD, are you doing a SQL select to read the value on every frame?

Yes. That was the point of my experiments, after I realized that good chunks of the data structures I set up for my game look suspiciously similar to indices and materialized views. So I figured, why waste time reinventing them poorly, when I could use a proper database for it, and do something silly in the process?

In a way, it's also coming back to the origin of the ECS pattern. The way it was originally designed, in MMO space, the entity was a primary key into component tables, and systems did a multiple JOIN query.