x -> needed
o -> optional

___________________________________________________________
WorldPersistence________________________________________   \
Planet_______________________________________________   \   \
Asteroid__________________________________________   \   \   \
MeetingPoint___________________________________   \   \   \   \
Obstacle____________________________________   \   \   \   \   \
Shape____________________________________   \   \   \   \   \   \
MeetingPointOwned_____________________   \   \   \   \   \   \   \
Fleet______________________________   \   \   \   \   \   \   \   \
Ship____________________________   \   \   \   \   \   \   \   \   \
FleetOwned___________________   \   \   \   \   \   \   \   \   \   \
Position__________________   \   \   \   \   \   \   \   \   \   \   \
PlayerOwned____________   \   \   \   \   \   \   \   \   \   \   \   \
Player______________   \   \   \   \   \   \   \   \   \   \   \   \   \
                    \   \   \   \   \   \   \   \   \   \   \   \   \   \
+--------------------+---+---+---+---+---+---+---+---+---+---+---+---+---+
| Game Objects       |   |   |   |   |   |   |   |   |   |   |   |   |   |
+--------------------+---+---+---+---+---+---+---+---+---+---+---+---+---+
| Player             | x |   |   |   |   |   |   |   |   |   |   |   | x |
| Ship               |   | x | x | x | x |   |   |   |   |   |   |   | x |
| Fleet              |   |   |   |   |   | x | x |   |   |   |   |   | x |
| Asteroid           |   | o | x |   |   |   |   | x | x | x | x |   | x |
| Planet             |   | o | x |   |   |   |   | x | x | x |   | x | x |
| MeetingPoint       |   |   | x |   |   |   |   |   |   | x |   |   | x |
+--------------------+---+---+---+---+---+---+---+---+---+---+---+---+---+