Shuttle loop

Shuttle Loops, also called Loops, are a common gameplay elements seen almost in every game in the Sonic the Hedgehog series. Shuttle loops are seen in almost every places of the world of Sonic the Hedgehog, where their origin is not known, but they are seen as part of the zone's or stage's scenery. They are different sized landforms, that have hole of loop-de-loop to go through. Some of them are seen to have platforms above the loop, while some of them have not. Land-forms have crafted numerous different versions of shuttle loops, although there are also seen in machinery, futuristic or urban-type of levels as well.

First seen in original 16-bit version of Sonic the Hedgehog, it usually consists of a loop-de-loop along the pathway. A character usually can't run through the shuttle loop unless they're running fast enough. They will fall to the bottom and be able to run out of it. As said before, there are numerous different types of shuttle loops seen through the series and have also made numerous appearances in other media, where they are not seen to have much purpose.

Overview
In Sonic the Hedgehog series, shuttle loops are seen in almost every platform title and even some of spin-off games. While not every level of each game, they are seen to be one of the most common elements in the series. The earlier games in the series for Sega Genesis are seen to feature more developed game engine with pinball-based physics than any video game before, the player could be easily able to create enough amount of speed to run or roll through shuttle loops or being launched to the air by ramps and hillocks. Shuttle Loops are also able to gain more momentum, if the player can perform Spin Attack, while running through loop-de-loop, similarly like in downhills. There are also other objects, which can easily gain more momentum to run the shuttle loop such as springs, dash panels or any other gimmicks.

Shuttle Loops are seen to have most of the time normal amount of ring strings being set on loop-de-loops, which the player can collect while running past by. It is also noticeable, that the player is able to climb on to the shuttle loop and outstrip above. There are usually seen to be huge amount of rings, monitors with different power-ups or other items and objects to be used. As the player can't reach there by jumping, there are always moving platforms near close of, that can lead to the top of the shuttle loop. Above shuttle loops can be also alternate pathways, but in numerous games, shuttle loops are not seen to have platforms above it, where to move or are part of the ceiling of the level. Alternate pathways also go sideways through the hole of loop-de-loops in few games. Numerous shuttle loops can also to be range of different formed, which can require more momentum and speed to be gained.

In later games, especially 3D games, the player doesn't need to gain momentum or speed, as dash panels can easily help the player through the loop-de-loops. Due of this, the backtracking in 3D games, can be hard, even several points impossible. Games such as Sonic 3D Blast and Sonic Chronicles: The Dark Brotherhood have automatic sections, where the playable character is seen going through loop-de-loops and lead to the another section of the level without having control to the character.

Stages with Shuttle Loops

 * Green Hill Zone
 * Star Light Zone
 * Emerald Hill Zone
 * Chemical Plant
 * Hill Top Zone
 * Angel Island Zone
 * Launch Base
 * Sandopolis Zone
 * Emerald Coast
 * Speed Highway
 * Seaside Hill
 * Ocean View (Sonic & All-Stars Racing Transformed track)
 * Westopolis
 * Leaf Storm
 * Water Palace
 * Mirage Road
 * Night Carnival
 * Huge Crisis
 * Altitude Limit
 * Dead Line
 * Frog Forest
 * Apotos
 * Spagonia
 * Molten Mine
 * Tropical Resort
 * Sweet Mountain
 * Planet Wisp
 * Radical Highway
 * Machine Labyrinth
 * Sylvania Castle Zone
 * Crisis City (Sonic Generations)
 * Windy Hill
 * Desert Ruins
 * Silent Forest

Trivia

 * In Super Smash Bros. Brawl, a Shuttle Loop can be seen in the background of arena Green Hill Zone with Tails, Knuckles, and Silver seen running through it constantly.
 * In some of the 2D side-scrolling Sonic games as the character runs on a loop, if the player inputs the character to jump while at the center of the loop, the character will actually accelerate.