Shuttle loops, also called giant loops, loop-de-loops or just loops, are common gameplay elements seen in almost every game in the Sonic the Hedgehog series, which are seen in numerous places around the world of Sonic the Hedgehog. Shuttle loops are different-sized landforms of unknown origin in the zone's or stage's scenery, that have a loop-de-loop which the playable character can run through as a part of the path. Shuttle loops also appear in numerous different versions crafted out of landscapes, though there are also shuttle loops in industrial, futuristic, or urban-type levels.
Shuttle loops were introduced in the original 16-bit version of Sonic the Hedgehog. Besides having appeared in the games on countless occasions, shuttle loops have also made numerous appearances in other media.
In the Sonic the Hedgehog series, shuttle loops are seen in almost every platform title and even in some spin-off games. While not every level of each game has shuttle loops, they are seen to be one of the most common elements in the series. The earlier games for the Sega Genesis featured a more developed game engine with momentum-based physics than any video game before.
In order to pass through a shuttle loop, a player must move at sufficient speeds in order to remain in contact with the surface of the loop, and will then exit on the other side. If a playable character is not moving fast enough, the playable character will fall down out of the loop, or not be able to scale the slopes. When moving through a shuttle loop, the player is able to either run or roll, if moving fast enough, through it. Also, similar to the real-life phenomenon of moving downhills, the shuttle loop can give the playable character more momentum should the player perform a Spin Attack while moving through the loop-de-loop. Numerous shuttle loops can also be differently formed with longer loop-de-loops, which requires more momentum on the player's behalf to be gained before the player can get through it.
Most of the time, shuttle loops have a certain amount of Rings set up in line on their loop-de-loops, which the player can collect by moving through them. Shuttle loops have flat platforms above the loop-de-loop that the player can stand on. On such platforms, there can usually be found a huge amount of Rings, Item Boxes with different power-ups or objects to be used, and even alternate pathways that the player can access. Because the player cannot reach the flat tops of the shuttle loops by jumping, there are always moving platforms nearby the shuttle loops that can take the player to the top of them. In numerous games, however, the shuttle loops do not have platforms above it to move on or are part of the ceiling of the level. Also, in a few games, alternate pathways can go sideways or through the hole of loop-de-loops.
In later games, especially 3D games, there can usually be found a Dash Panel just before a shuttle loop begins, eliminating the need for the player to gain momentum before entering a shuttle loop. Because of this, backtracking in the levels of the 3D games can be hard, if not impossible. Games such as Sonic 3D Blast and Sonic Chronicles: The Dark Brotherhood have automatic sections of the shuttle loops where the playable character goes through them to another section of the level without the player having to control the character. In Sonic Runners, the playable character has to automatically perform a Spin Attack in order to pass through loops to collect Rings, or the player moves past it instead.
List of shuttle loop types
|Regular loop||The most basic type of shuttle loop that is located on flat terrain and has a platform directly above it with items, enemies, or other objects set there. It can also be seen between the ground and the ceiling, in which case it will not have a platform above it. They are easy to go through while backtracking in the level. In Egg Utopia in Sonic Advance 2, the player can go through these loops while gravity is reversed.|
|Downward guiding loop||Another basic type of loop, downward guiding loops will guide the player directly down to a lower part of the level, but will sometimes have a small ramp at the end to further direct the player. Similarly to regular loops, they can have platforms directly above them but are most often found in between the ground and a ceiling. These are difficult to backtrack through, as the player must build up a great amount of speed before doing so. The downward guiding loops in Marble Garden Zone lead to corkscrew poles that deposit Sonic on either the left or right of it. The player can jump off during this sequence to end up on a preferred side.|
|Downhill loop||These shuttle loops are found on downward facing hills, which can give a large amount of speed if the player rolls into a ball while going through them. Like previously mentioned loops, they may have platforms placed directly above them. While they are not as hard to backtrack through as downward guiding loops, the player still has to build up speed before attempting to do so.|
|Tall loop||These larger shuttle loops have alternate pathways going through the hole of the loop itself. The player may be unable to get through these loops normally, but if they are launched by a spring or Dash Panel beforehand, they will be able easily move through one. Depending on the game, it can be impossible to backtrack through these loops.|
|Automatic pinball loop||These loops are similar to downhill loops, however they are found only in casino zones, and the player automatically moves through of them after being launched by Pinball Shooter. If the player doesn't have enough momentum, the playable character will roll back down to the Pinball Shooter and must try to get through it again.|
|Down tunnel leading loop||
They are mostly similar to downward guiding loops, which only lead to tunnels below the loop. In Hill Top Zone and IceCap Zone, these tunnels are blocked with breakable blocks, which the player has to destroy by performing Spin Attack on the loop. After entering to the tunnel, it will soon lead to the another place on the level.
|Tunnel/Pipe loop||Loops have also been placed in underground tunnels or high-speed warp tubes in certain games. These sections are automatic, as the player is unable to control their character when going through them. In Sonic Advance 2, large and long horn instruments are seen making a loop which the player can go through. It is impossible to backtrack through these loops in any game.|
|Deadlock loop||Very rare types of shuttle loops, these are only seen in Sonic the Hedgehog CD. They send the player back in the direction they came from. They are seen to have a small platform above part of the loop-de-loop, while the bottom part has a block in the center with springs usually being set to lead out of it.|
|Crossing loop||Only seen in Angel Island Zone Act 1, where one of the downhill loops crosses two pathways together. The upper one goes downhill as normal, while the lower one comes from the bottom pathway and leads to the upper loop.|
|Bottom corner loop||In IceCap Zone Act 2, these types are usually on the bottom of downward guiding loops and are oppositely positioned to walls. The player can gain a large amount of speed by rolling while going through this loop. It is impossible to backtrack through these loops.|
|Underground launcher loop||If the player enters the right pipe, a launcher will automatically boost the player through the loop and shoot them upwards, where another launcher loop may be. While they are shown to be mechanized in Launch Base Zone, they are not in Neo Green Hill Zone. Jumping to the upper pipe will fire the player backwards.|
|Tubular loop||These loops are similar to many other shuttle loops. The only difference is that, while they aren't part of ceilings, they don't have any platform above them which the player is able to walk across. In Mushroom Hill Zone, some of them can lead to falling (such as in the picture on left). In 3D games, these types have been frequently used.|
|Upward guiding loop||Another general type of shuttle loop, which is similar to a downward guiding loop. However, these are usually located on an upper part of the level, and the player must use a Dash Panel or spring in order to get enough momentum to travel through them. They are easier to backtrack through than some of the other shuttle loop variations.|
|Multispinning loop||Another type of shuttle loop, in which when the player enters the loop-de-loop, it will make the playable character automatically run through the loop two or more times, until the loop ends.|
|Ring shooter loop||After being launched by a Ring Shooter, it can sometimes send the playable characer(s) through several mid-air loops, while guiding the player to the other side of the level.|
|Giant loop||One type first seen in Sonic Advance 2. Giant loops are very similar to other kinds of loops, although the player needs to have huge amount of speed to get through these. In Leaf Forest Act 2, there's a giant loop that has large hole on the top of it. Some giant loops may have platforms on top of them, and they are frequently seen in 3D games.|
|Giant three-way loop||One of the frequently seen types featured in Sonic Heroes. It is a basic giant loop that is separated to three different ones side by side. Each of the three members on the playable team can use these to get power-ups from item boxes on each loop. In Sonic Generations, they lead to three different pathways, which the player can choose.|
|Inverse loop||These types of shuttle loops are not usually seen, as they are set below the ground. The player has to gain a large amount of speed to swing the playable character around them. They are sometimes set dangerously over bottomless pits.|
|Rail loop||A more recent type of shuttle loop, these are made out of different grind rails. The player can go through them easily by using Dash Panels set before the loops.|
|Long loop||These types of shuttle loops are similar to regular ones, but take slightly longer to go through. The player must have gained a certain amount of speed to get through these.|
|Disintegrating loop||These loops are made of sand. They function much like normal loops until the player runs through one, at which point it will evaporate.|
- One of the many unfixed glitches in Sonic the Hedgehog (2006) involves the playable characters in the game being able to walk through, and even stand upside down at the top of, shuttle loops without falling.
- 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.