Write a guide about the GOM

docs/discussion/gom.rst

@@ -0,0 +1,39 @@
+=============
+The Game Tree
+=============
+
+Games in PursuedPyBear organize their objects into a tree, with the
+:class:`.GameEngine` as the root, and then :class:`.System` and :class:`.Scene`, and
+then :class:`.Sprite`.
+
+.. figure:: gom.drawio.svg
+
+
+Game Objects
+============
+
+All of these are instances of :class:`.GameObject`, which manages things like
+tree operations and children searching and such.
+
+Other than the :class:`.GameEngine` and its direct children, you may structure the
+tree however you want. You can define your own game objects and put them in your
+scenes (they won't render, but they'll receive events).
+
+
+Event Dispatch
+==============
+
+Events are dispatched breadth first: top to bottom, starting from the
+:class:`.GameEngine`, and then all of the :class:`.System` instances, and then the
+:class:`.Scene`, and then their children.
+
+In the above diagram, events would be dispatched in the following order:
+
+1. Engine
+2. System
+3. System
+4. System
+5. Scene
+6. Sprite
+7. Sprite
+8. Sprite

docs/discussion/index.rst

@@ -11,5 +11,6 @@ advanced users.
 
    values/index
    assets
+   gom
    maintenance-schedules
    default-branch