A guide to completing World 4-1 in Super Mario Bros 1 for the Nintendo Entertainment System.

Explore World 4-1

Go to the right to find a Piranha Plant coming out of a pipe. To the right of that, there are two ?-mark blocks. The bottom block contains a Mushroom or Fire Flower. Above the blocks, you will see a Lakitu, which drops Spiny Eggs. When the eggs hit the ground, they turn into Spinies, which are similar to Koopas, but with spikes on top. You'll get hurt if you try to jump on top of a Spiny, so don't do it.

You can try to jump onto the uppermost block and hit Lakitu with a fireball if you're Fire Mario, or jump on Lakitu if not. (Be aware that if you jump and are in the area with the letters and numbers, you can't shoot fireballs until you're below the level of the letters and numbers again.) Otherwise, Lakitu will follow you through the whole level, dropping Spiny Eggs.

Go to the right, jump over the gap, and there are four coins you can take. To the right, there are four ?-mark blocks that all contain 1 coin.

Go to the right, jump over the gap, and you find four ?-mark blocks in a row. They all just contain 1 coin. Jump on top of the ?-mark blocks, and stand on the second block from the right. if you collected all the coins in World 3-3 without dying, or if you warped to 4-1 via Warp Zone, you can jump straight up to find a hidden 1UP mushroom.

If you got rid of the Lakitu earlier, another Lakitu will appear in this sky here. You can't get rid of this one yet, so for now, go to the right and jump from the pillar of bricks to get the four coins on the right.

Go to the right to find a Piranha Plant pipe. When the Piranha Plant is gone, jump on the pipe, then jump to the right to get the four coins there. Go to the right and there is a second pipe. If you're small, you can get more coins by going down this pipe than you could get by skipping the pipe, and there is a brick with a Mushroom in the secret area as well. So if you want more coins, let a monster hit you if you aren't small already, then go down the pipe, get all the coins, then hit the brick on the right to get a mushroom, and enter the pipe to exit the secret area. Otherwise, go to the right from the pipe to reach an area with 10 ?-mark blocks, where you can jump on top and stomp the Lakitu or hit it with a fireball. In the bottom-left group of three ?-mark blocks, the rightmost one contains a Mushroom or Fire Flower. Go to the right from there to find a Piranha Plant pipe. If you went to the secret area, this pipe is where you will come out.

Go to the right, jump over the gaps, and carefully jump over the pillar of blocks and the gap after it, avoiding the Spinys from new Lakitu that has appeared.

There are stairs to the right, but before you jump to the goal pole, there is a brick to the right of the stairs that you can optionally hit to get coins, then jump from the top of it onto the goal pole. Then you will continue to World 4-2.