Data model fundamental: for many classes/entities, there are two versions e.g. Foo and GameFoo. Foo represents
the thing in its beginning state -- essentially these capture the "scenario" in game parlance. GameFoo represents
a version of Foo with state belonging to an actual play(ed) game instance.
So, Node seed data would capture a starting template for a node. Then an individual in-progress game will create GameNodes as necessary that correspond to the scenario Nodes and capture state for that particular game.
Right now these are tightly coupled. A GameNode for example delegates its description attribute to Node. So if the underlying node description changes, that change will be visible in in-progress games with a related GameNode. This might need to change in the future if we want to introduce e.g. versioning of scenarios that are opt-in for in-progress games.
TODO: game_foo is used much more in the code than Foo so we should probably invert this relationship, so that Foo is understood to apply in a single game and the parent is something like ScenarioFoo. Would be a nice thing for brevity/code clarity.