Like any decent web application, this game does not work on Internet Explorer.
Santa's Christmas Adventure

It's Christmas Eve and you are the chief elf at Santa's Grotto. Your job is to make sure everything runs smoothly as Santa delivers presents to the entire world in just one night! For some reason, you have an unusual sense of foreboding... As you progress through the levels of the game, more details of the metamodel will be revealed to you. Use the Model Explorer to query the model with EOL and answer the questions on the right!

Level 1 of 10

First things first, we need to get the sleigh ready.

Copy and paste the solution below into the Model Explorer and click on the magnifying glass to reveal the answer.
// We'll give you this one
@namespace(uri="xmas", prefix="") 
package xmas;

class Xmas {
  val Object[*] objects;

abstract class Object {

class Reindeer extends Object {