Minecraft is a work of art.
With your bare hands, you collect dirt and wood and then you can start crafting tools. Suddenly the possibilities start opening up. Your wooden pickaxe allows you to dig out stone, which you can use to make a stronger pickaxe, or maybe a shovel. Behold! You discover iron ore and can now make even stronger tools! Or maybe a sword.
Oh, and then the sun sets and you're left alone... or are you? Monsters lurk in the dark. Without a source of light, caves are literally frightening, but now the entire world is a scary place. With your collected resources, you must build a shelter to survive.
For a game that has no rules, no linearity, no structure, it's the most fun I've had in probably 10 years playing a computer game.