Free fall from the top of the world (build limit) to the bottom of the world and survive

Befriend twenty stray Cats.

Create an Iron Golem.

Power a Furnace with Lava.

Eat a Notch Apple.

Brew a potion.

Use a saddle to ride a pig, then have the pig get hurt from fall damage while riding it.

Swim in lava while having the Fire Resistance effect.

Gather all 16 colours of wool.

Travel by minecart to a point at least 500m in a single direction from where you started.

Complete HARM Challenges I to V

Open 100 strongboxes

Play for 100 days.