Finish the catapult zone.
Finish the trebuchet zone.
Finish the ballista zone.
Finish the battering ram zone.
Finish the gunpowder barrel zone.
Finish the cannon zone.
Finish the lightning cloud zone.
Finish the rain cloud zone.
You are a monster!
Finish Sunny Fields.
Finish Wintery Weather.
Finish A Rainy Day.
You seem to really like the main menu... for some reason.
Finish the spring zone.
Finish the arrow trap zone.
Finish the firespitter zone.
Finish Ancient Ruins.
Complete the secret level from Ancient Ruins.
You have completed World 1!