World 2-1 (Super Mario Bros.)

World 2-1 is the first level of World 2 in Super Mario Bros. The level has many gaps and enemies as well as a Spring in front of a big wall at the end.

Layout
At the start of the level, there are three brick blocks, the middle one containing a Mushroom, or a Fire Flower if the player is Super Mario. Just after, there is a short brick platform with a Goomba walking down it. Then the platform goes into a small gap with two Koopa Troopas in it.

After the gap, there are two more Goombas followed by a Piranha Plant in a Pipe. Next, there are two rows of ? Blocks. The one in the bottom row to the far left contains another Mushroom or Fire Flower. There are also more Goombas and Koopas on the ground.

Halfway through the level, there are more brick blocks, one even containing a Star on the top left, as well as another Piranha Plant inside of a Pipe.

Next, there are even more rows of ? Blocks and brick blocks. The ? Blocks all contain Coins. There is also another set of Goombas walking on the ground below the blocks. One of the blocks on the top row slightly to the left contains a Vine that Mario can climb to access a secret area.

The Secret area leads into the clouds where Mario can ride a platform moving to the right to collect a bunch of Coins. After Mario exits the secret area, he ends up at the end of the level.

Next, there are a few more groups of Goombas and a bunch more Piranha Plants in Pipes. The first Pipe leads to another secret area, this one leading undergound, offering another bunch of Coins for Mario to collect.

Then, there is a short gap followed by a Koopa Paratroopa. Then there is another short gap with three vertical blocks that Mario must jump over. Then, there are some more ? Blocks as well as brick blocks, mostly containing Coins. There are also even more Goombas and Piranha Plants in Pipes.

Lastly, there is another Koopa Paratroopa and a short gap. After the gap, there is a Spring, followed by a big brick wall. The player must press the "A" button right when Mario is standing on the lowest point of the Spring to make him jump super high, reaching over the brick wall and getting to the Flagpole. Alternatively, there is a Hidden Block above two Brick Blocks. The player can use it to jump over the brick wall.

Enemies

 * Goombas
 * Koopa Troopas
 * Piranha Plants