/**
 * The package playground contains all level specific logic and control of level logic.
 * The structure and general logic (with global and local flags to be stored/used) 
 * is provided in abstract base class {@link Playground}.<br>
 * Child-classes implement specific logic for one level and game type (e.g. {@link SpaceInvadersLevel}).<br>
 * 
 * Generally, the base class {@link Playground} supports totally different game types to be implemented.
 */
package playground;