The fourth world that Mario and crew enter is encased with ice. Watch your step, because it's slippery! If you fall, there's nothing to save you here. To make things worse, enemies like Flurry, Autobomb, and your old pal Shyguy will be on your heels. Got any ice skates?
No traction. Slippery is definitely the one word that best sums up map A. Get a feel for how your character moves on the ice. You'll need to stop well in advance if you don't want to crash into an enemy. Better yet, jump in the air. Surprisingly, you have better control when your feet are off the ground than on.
(1) Sub-space 1. It's going to take plenty of skill, know-how, and nerve to get from here to Sub-space. Be sure to take potions because you're going to need them as never before. Here's a hint: create doors whenever Flurry is not around.
(2) Sub-space 2. You're finally at the end of map A. Good going. How about taking a quick break to build up your strength? These rocks aren't slippery, so you don't have to worry. Grab the potion from the top and set it down right where you found it. Be careful, ice is still slippery in Sub-space.
Rocket Ride! Now that you've got the Mushroom, it's onto the next world. Hold it—there's no passage! Just grab a handful of grass and you'll find a rocket in your hands. Climb on board and you're off to map B.
(3) Get the best of Autobomb. The Autobomb follows you everywhere and shoots flames at you. Here's another hint: get rid of Shyguy and get above Autobomb. And look—Autobomb will give you a lift! This will especially come in handy in, where you are required to get a boost in order to reach the A-coin here.
(4) Where's the boss? You've made it to the end of World 4-1, and you probably expected to find a mini-boss such as Birdo waiting for you. No such luck. Don't be disappointed, it was hard enough getting here. Enjoy the breather. Grab the Crystal Ball and head through the hawkmouth gate.
Not much advancement: There's very little change in this world between the original and the updated version in. The most significant change that you will discover are at these two jars at the end of the world. They aren't much, but you can find some interesting items inside of them if you take the time to explore them.