x -> needed
o -> optional

____________________________________________________________________
WorldPersistence_________________________________________________   \
Planet________________________________________________________   \   \
Asteroid___________________________________________________   \   \   \
MeetingPoint____________________________________________   \   \   \   \
Obstacle_____________________________________________   \   \   \   \   \
Shape_____________________________________________   \   \   \   \   \   \
FleetOrbiting__________________________________   \   \   \   \   \   \   \
FleetMoving_________________________________   \   \   \   \   \   \   \   \
Fleet____________________________________   \   \   \   \   \   \   \   \   \
ShipOrbiting__________________________   \   \   \   \   \   \   \   \   \   \
ShipMoving_________________________   \   \   \   \   \   \   \   \   \   \   \
Ship____________________________   \   \   \   \   \   \   \   \   \   \   \   \
FleetOwned___________________   \   \   \   \   \   \   \   \   \   \   \   \   \
Position__________________   \   \   \   \   \   \   \   \   \   \   \   \   \   \
PlayerOwned____________   \   \   \   \   \   \   \   \   \   \   \   \   \   \   \
Player______________   \   \   \   \   \   \   \   \   \   \   \   \   \   \   \   \
                    \   \   \   \   \   \   \   \   \   \   \   \   \   \   \   \   \
+--------------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| Game Objects       |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+--------------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| Player             | x |   |   |   |   |   |   |   |   |   |   |   |   |   |   | x |
| Ship               |   | x | x | x | x | o | o |   |   |   |   |   |   |   |   | x |
| Fleet              |   | x |   |   |   |   |   | x | o | o |   |   |   |   |   | x |
| Asteroid           |   | o | x |   |   |   |   |   |   |   | x | x | x | x |   | x |
| Planet             |   | o | x |   |   |   |   |   |   |   | x | x | x |   | x | x |
| MeetingPoint       |   |   | x |   |   |   |   |   |   |   |   |   | x |   |   | x |
+--------------------+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+