What is the most efficient way to achieve "End Game" in Secret of the Magic Crystals?

In "Secret of the Magic Crystals", the hardest achievement (0.7% completed) is called "End Game" and is described by the following sentence:

By the power of the Magic Crystals I was able to bring this Story to a Happy Ending!

After some research on the Internet, I understand this achievement consists in breeding five different level 5 magical horses for the quest to uncover the secret of the magic crystals, one of each type:

  1. Unicorn: The grace and beauty of this horse is one of a kind.
  2. Pegasus: The Ancestors of this Colt were unique racehorses.
  3. Fire Steed: This colts ancestors were fearless and wild by nature.
  4. Ice Steed: Mountain People Bred this kind of muscular horse.
  5. Demon Steed: People of forgotten civilizations passed on the secrets of breeding this type of horse.

However, the stable contains only six different slots. And to get a level 5 horse, I need two level 4 horses and one empty slot, which would suggest I need to sell the level 5 horses, based on the pigeonhole principle.

So what is the most efficient way to achieve "End Game" in Secret of the Magic Crystals?


It's either gathering the second crystal or acquiring your second level five horse to unlock more space in your stable. I'll confirm which later.