System can execute in priority order, by default all systems are priority 0. Lower values indicated higher priority. For a system to execute before all other a lower priority value (-1 for example) must be set. For a system to execute after all other a higher priority value (10 for example) must be set.
Determine whether the system is called in the SystemType.Update or the SystemType.Draw phase. Update is first, then Draw.
The types of entities that this system operates on For example ['transform', 'motion']
Systems observe when entities match their types or no longer match their types, override
An Excalibur System that updates entities of certain types. Systems are scene specific
Excalibur Systems currently require at least 1 Component type to operated
Multiple types are declared as a type union For example: