As with the original Super Mario Bros., the “?” Blocks are encountered as soon as the game begins. Since they utilize a fairly universal symbol for a question, they inherently invite the player to investigate.
In addition to being positioned over Mario’s head, a slowly approaching Goomba encourages the player to jump up and discover that hitting the blocks from below can yield rewards (in this case, some Coins and a Super Mushroom).
The red Venus Fire Trap is also introduced here and — in typical Mario fashion — doesn’t respawn if killed and only comes out if Mario isn’t standing next to its pipe (or on top of it). Although the player can’t go down this particular pipe, the fact that an enemy emerges from it hints at the possibility of Mario being able to do the same.
If the Koopa Troopa is touched while in this state, it quickly slides away from Mario. Although the big white block is a bit in the way, the player can still accomplish this feat fairly easily. If he does, he’ll learn that shells can be used to activate “?” blocks (which is the only way to do it in this case as the block cannot be hit from below) while discovering the game’s new powerup: the Super Leaf.
Immediately to the right, a strip of flat land with three enemies — one of them a red Paragoomba — lets the player experiment with Raccoon Mario’s glide and spin-attack mechanics.
Following the three Goombas (which don’t respawn if killed, leaving the strip clean of enemies), a diagonal trail of coins leads up into the sky. The player must jump over a bottomless pit at the end of this runway and is encouraged to collect the coins, so it makes sense for him to get a running start and jump as high and far as possible.
When the player starts running, a HUD meter fills up, the running animation changes, and an urgent sound effect begins looping in the background. All these events signify that something important is happening, and when the player jumps and soars into the sky, the screen — for the first time in a Mario game — begins to scroll horizontally and vertically at the same time.
As soon as Mario lands on a series of clouds, he finds an isolated Brick Block that floats in the air much like the “?” blocks. This similarity encourages the player to interact with it in much the same way, i.e., by hitting it, which yields the first 1-Up Mushroom.
The clouds continue to the right creating another clear runway that ends with a trail of coins. In a dare of sorts, the coins ask the player to throw caution to the wind and make a blind leap into the unknown. The newly acquired flying ability is quite thrilling and liberating, and having just earned an extra life, it stands to reason that most players would want to pursue the extra treasure. Doing so takes Mario off-screen and gradually lowers him by a tall pipe.
With no other obvious place to go, the game stresses the significance of the pipe. If the player figures out how to enter it, its path leads him to a neat little Easter Egg: a room filled with coins that are arranged to form the number 3.
If the player misses the opportunity to fly up to the cloud passage, the next two sections serve to introduce some new enemies. The first contains a green Koopa Troopa and three green Koopa Paratroopas that drop from the sky (hinting that there’s something up above). The Paratroopas demonstrate their ability to jump onto and fall down from platforms, while the two pits to the sides serve as an opening to show that enemies can also fall to their deaths.
The second area contains a Piranha Plant and a green Venus Fire Trap. Their proximity makes it more likely that the player will have to stop by one of them on his route to the level’s end. If he does, he’ll have another opportunity to discover that the plants can’t come out of pipes if Mario is standing near them. The immobile version of Super Mario will also encourage the discovery of crouching in order to dodge the fireballs, and a Raccoon Mario will get a chance to dispatch the plants with his spin-attack.
Right before the level’s end, the player encounters two grounded piles of Brick Blocks. Since the player had two previous chances to pick up a Super Leaf, he’s likely to try the spin-attack on these glowing objects as there’s no way to hit them from below.
In addition to this lesson, there’s also a solitary red Koopa Troopa pacing atop the second group of blocks. Since the player already had a few chances to learn that Koopa Troopa shells can take out other enemies and activate powerups, he might try to do the same here. If he does, the shell will break through a bunch of Brick Blocks and leave one of them unobstructed. If Mario hits this block from below (or spin-attacks it from the side), it will reveal a P-Switch.
The P-Switch functionality immediately turns all the remaining bricks into coins and plays a jaunty countdown theme. When the countdown ends, the remaining coins turn back into Brick Blocks, teaching the player that the transformation is only temporary. The music change is important as there are no other visual cues to indicate if and when the blocks will return to their original form.
The final part of the stage is segmented by a jagged black line that spans the height of the map. This clearly denotes the end of the level while keeping with Super Mario Bros. 3′s stage motif — crossing this boundary is almost like stepping behind a curtain.
The only object in this area is an animating Goal Panel that instantly draws the player’s attention and ends the stage when touched. Since the floor leading up to it is flat, it encourages the player to run in at full speed and jump into the panel. More often than not, this rewards the player with a star, the best possible Goal Panel prize.
I did not write this article and the original source is available upon request.