Koopa Troopa Cave

Koopa Troopa Cave, otherwise known as World 1-2, is the second standard course of World 1 in Super Mario 3D World. The course takes place in an underground cave with Koopa Troopas, Goombas, and Clear Pipes. It is unlocked by beating Super Bell Hill, and its completion unlocks Chargin' Chuck Blockade and a Toad House.

Koopa Troopa Cave additionally appears in the background in Super Mario Maker 2, in the underground theme of the Super Mario 3D World style.

Layout
The course starts on a grassy hill with a Koopa Troopa and a Warp Pipe nearby, which leads to an underground cavern filled with Koopas and Goombas. Near the beginning of this cave is a Clear Pipe that leads to a section with a Koopa Troopa and a ? Block. To the right is an area with some pipes and a hidden 1-Up Mushroom. Following this is an area full of cloudy platforms; at the top is a straightaway, and a Clear Pipe that leads to an area with three opening. One contains a golden Warp Pipe that has three Koopa shells; the other two contain Goombas. Past this section is a Warp Pipe that leads to an area full of Goombas, with a Star near the top, and a nearby Warp Pipe leading to the Goal Pole.

Green Stars

 * Green Star 1: Right before the checkpoint, the first Green Star can easily be found between some levitating cloud platforms.
 * Green Star 2: The player needs to climb three purple blocks to find a purple Mystery Box. Inside, they must defeat two Koopa Troopas to reveal the second Green Star.
 * Green Star 3: Near the end of the level, player finds a Goomba Tower with the final Green Star in the middle of the stack.

Stamp

 * Just after the Clear Pipe to the last room, there is a rectangular ? Block. The player must get on top of it and jump to reveal a hidden rectangular ? Block. Jumping on top of that block reveals another, allowing them to reach a ledge. The player can then enter the Clear Pipe on the wall to warp into an enclosure below the ledge, containing the Stamp and several Coin stacks. The stamp is a Coin.

Secret Warp

 * Cat Mario is required. Slightly to the right of the clear pipe leading to the stamp, Cat Mario must climb the wall to reach the ledge with an orange Warp Pipe that leads to World 2.

Enemies

 * Koopa Troopas
 * Goombas
 * Mini Goombas
 * Goomba Tower