There's something really emotional with Minecraft's (the game) ending.
Let's exclude the player and their knowledge that the game is simply a game.
You find yourself in a world all alone, where everything seems normal at first. Your instinct tells you to find resources and create a shelter for upcoming danger.
Once the sun set, monsters start to roam the earth, all set out to hunt and kill you.
When they do manage to hunt you down and slowly end you, fear flashes into your mind, but the moment they strike the final blow, a temporary darkness settles, and you find yourself either in the place you first appeared in, or your bed. Confusion and fear fills you, but your instincts yell at you to run back to where you died, and gather all the things you've dropped upon your death.
The loneliness fills you with sorrow and dread, and you decide to explore the world to take your mind off of that nasty feeling. As you travel from one corner to another, you discover more about the world, the residents, the wars, the history. Ancient cities and forgotten entities, all tell a tale of ancient ones of your kind who resided within this realm. You feel the urge to explore more, to learn more about your history, to find the ending and what truly happened to them.
You then find a portal, broken but still a portal. Through experimentation, you find the right way to open it, and once you entered it, you felt the heat of the hellish flames and heard to whispers and cries of sorrow of the Nether's residents. You find more relics, and discover more of the world's habitants, all while you try to reach back to the portal and return "home".
You continue on your journey.
You looked at every corner, every cave, and found another portal, but this time, it's different from the last one. But just like before, after a bit of experimenting, you managed to open it, and you jumped into the portal.
You find yourself in a completely different world. No trees, no water, no fire, only darkness and despair. The residents are tall and lanky, but you feel a certain familiarity to them. Instincts tell you to kill the monstrous creature, but you wonder what it was, until you looked up. A dragon, a dark dragon with the same colors as the tall and lanky creatures. Through sheer determination, you ended the life of the dragon, and with a burst of light, it was gone.
You find another portal, one that opened after the dragon's death, and jumped into it. And all you can see is darkness.
But, you feel an unknown presence in the darkness with you, as you listen to them monologue. Your head is fuzzy, their voices muddled, but before you passed out in the dark, the last you heard was "And the universe said I love you".
You open your eyes, and find yourself in your bed, with everything you've collected in your journey with you. You felt as if you had a dream, but everything you have just proves to be evidence that it was indeed real.
You remembered the voices, and just what they said. You smiled. You continued in your journey, now with the knowledge someone out there is waiting for you to come back home.