World 1 in Super Mario Bros. 2 was the first area Mario, Luigi, Princess Peach, and Toad ventured through. It was divided into three levels. As they traveled, the heroes were attacked by Tweeters, Shy Guys, Snifits, and Pidgits. At the ends of the first two levels, they had to face the egg-spitting Birdo, and at the end of the last level, they had to fight Mouser.
World 1 starts with your character dropping down from a doorway suspended in mid air. At the bottom of the screen, there is another doorway, which leads outside. There is an extra 1-UP disguised as a plant next to a POW on top of a hill. There is a shortcut to Birdo that can be found in the cave area halfway through the level. After climbing up the vine, instead of exiting to the right to the normal exit, jump across the waterfall and use bombs to blow up blocks. After going through the door on the other side, proceed to the right and Super Jump over the wall on the right side of the screen, and you will be at Birdo.
At the start of the level is a Magic Carpet that needs to be hijacked in order to get across the large pit. Afterwards there are two vases - the first has a 1-UP at the bottom, and the second has a key for opening the locked door.
This level features a hidden warp to World 4. Right before the castle, there will be a cluster of plants, one of which is a magic potion. Take the magic potion past to the far right of the screen, past the castle, to a pipe. Use the magic potion to create a door, enter the door, enter the vase while still in dream land, and the player will be warped to World 4.
For the normal exit which will lead to World 2, enter the castle as normal and at the end you face Mouser.
Ace Coin locations in Super Mario Advance
The first one is under the level when the player gets on the Magic Carpet. The next one is at the top somewhat directly under the first one. The third one is in a cave, a Key is needed to open it. This coin is seen when getting out of the cave and going left. This coin is seen by the last door.
In the GBA Version, World 1-1 got the most changes of all the levels in World 1.