New Super Mario Bros./World 1-4

Slide down slopes on this hilly road and take down enemies in your way! Bowser Jr.'s troops continuously spawn from warp pipes, replacing any fallen Goombas in an instant. Mini Mushrooms get an official introduction here. Use it to access secrets and soar over enemies!

Level walkthrough
Immediately to the right of where you start is a slope. Crouch when you're on the slope to slide down, which should let you take out three Goombas along the way. Up the next hill is a green Koopa, which serves to introduce a new technique. Stomp the Koopa, then throw its shell down the hill. It will hit a grounded question mark block that contains a power-up, and you can use this technique as an alternative to ground pounding for any similar blocks, especially if you're Small Mario. Run up the next hill and jump down into a small valley. You can ground pound the leftmost block for a bunch of coins, then hit the rightmost block for a Mini Mushroom. This will turn you into Mini Mario, which lets you enter tiny warp pipes, jump extra far and run on water. However, you will die in one hit and you can only use ground pounds to stomp enemies, so this power-up is more for getting secrets than for survival.

You can get a quick demonstration of your newly-gained abilities by running through the small gap to the left of the green warp pipe, then enter the smaller warp pipe. This takes you to a colorful bonus room. Keep dashing to run across the water, then wall jump to get a Star Coin. To return to the main course, take the large warp pipe out. Past the valley where you got the Mini Mushroom is the first appearance of a green Koopa Paratroopa. These flying Koopas can take two hits before ducking into their shells, and they have different attack patterns while they have their wings. This one only hops slowly toward you, so you should have no problem avoiding it. Over another hill is a green warp pipe that spawns endless Goombas, as well as a power-up block in the middle of the second set of blocks. A Super Mushroom will make you grow back to normal size if you're Mini, so it is recommended that you collect it to for an easier time attacking enemies.

You will reach another green warp pipe, as well as a convoluted collection of brick blocks. Stomp the red Koopa and grab its shell, then get to the top of the brick block structure. Release the shell and watch it break through the brick blocks tier by tier, knocking into some brick blocks on the way. It will also hit a 1-Up block, but you will have to avoid the red shell while you collect it, as it will otherwise fall into a gap. By the time the shell stops ricocheting, the blocks by the green warp pipe should be cleared. Go down the pipe to an underground chamber. Avoid collecting any coins here and go straight to the right. Hit the rightmost block to make a P-Switch pop out, then jump on it to turn the brick blocks into coins and vice versa. If you did not collect any coins in this area, you can use them as platforms to jump to the ceiling. Run left to grab the second Star Coin! Go into the right warp pipe to return to the surface.

Back outside, be sure to travel left so that you don't miss anything. The checkpoint flag is located soon after the brick structure from before, below a red warp pipe that keeps spawning Goombas. From the checkpoint, go over the hill to see the third Star Coin. As Small Mario, you can dash over the one-tile gap into the small pocket, letting you collect the Star Coin. Over the hill above the Star Coin, you will return to where you emerged from the warp pipe. There is one more hill before the flagpole, but you must still watch out for the Goombas coming out of the yellow warp pipe. Get a running start from the base of the warp pipe and jump so that you grab the top of the pole.

The path splits from this level to the castle. World 1-4 is immediately available to you and is arguably easier, with a green Toad House that requires 5 Star Coins. Meanwhile, you can spend 5 Star Coins to get to Level 1-A, which unlocks a red Toad House upon completion instead.

Star Coins

 * 1) In a bonus room accessible through a tiny Warp Pipe, which requires you to be Mini Mario. Wall jump to collect it.
 * 2) In an underground area through a warp pipe partially sealed by a brick block. Hit a question mark block to make a P-Switch appear, then activate it and run across the newly-created platforms to reach it.
 * 3) In a small pocket of space. Run quickly across the gap as Small Mario to get it.