Datomic, though, isn't Datalog syntax at all. I've got nothing against Datomic, but can't help to think learndatalogtoday is outright false advertising by tryi

Datomic, though, isn't Datalog syntax at all. I've got nothing against Datomic, but can't help to think learndatalogtoday is outright false advertising by trying to capture "Datalog" as SEO term for a proprietary graph database which has nothing to do with Datalog/Prolog. The point of Datalog is that it's a subset of Prolog syntax, implying that engines can be reasonably exchanged for one another. But this is only possible with real Datalog, or SPARQL for that matter.