Sequence Breaking

A Sequence Break is an act that breaks the standard sequence of events in a game ("taking another way through the game than a player is likely to use on the first play-through"). This may amount to collecting an item earlier than intended or skipping a segment entirely. Sequence breaks often rely on glitches, but sometimes creative thinking is enough. Efficient sequence breaking is the key to most time improvements in speed running. For example, in Metroid: Zero Mission, it is possible to kill Ridley before killing Kraid, and also to obtain the Varia Suit before the Ice Beam.

Sequence breaks are ubiquitous in the Metroid games. In fact, many sequence breaks seem to have been known to the developers. For instance, the secret Wall Jumping and Bomb Jumping techniques in Super Metroid directly lead to several sequence breaks, but these moves mostly lack practical use otherwise. Further, it is nearly impossible to get stuck or cause crashes in Super Metroid when entering areas without the supposedly required equipment, indicating that the designers were aware of the possibility that players would do so.

Most re-releases of games correct speedrunning techniques to prevent sequence breaks from occurring.

List of Sequence Breaks

 * It should be noted that most of these glitches have been fixed in Metroid Prime Trilogy for the Wii. Only the Nintendo GameCube versions of Metroid Prime and Metroid Prime 2: Echoes have all of the glitches present.

Metroid

 * A "Bomb Boost Jump" can be performed by laying a bomb and unmorphing before it detonates. Samus will be sent into the air by the bomb, and she can jump higher than normal.
 * If Samus rolls off a ledge in Morph Ball form and unmorphs, she will be in her standing sprite, and she is able to jump. This is similar to the Jump Boots, and the technique can also be performed in Metroid II.
 * The Varia Suit can be collected without the Ice Beam by Door Jumping up to the Varia Suit's room in the shaft that is two rooms from the Varia's location.
 * The Varia can also be collected without the High Jump Boots but with the Ice Beam. Samus must abuse a Waver by freezing it over and over to get to the Varia. The Waver may not always line up correctly, and if this is the case, Samus should use the Ice Beam-less method.
 * Ridley's Lair or the area leading to the High Jump Boots can be reached without the Bombs by using the Door Jump in the "green bubble" area of Norfair.
 * The Ice Beam can be collected without the Bombs by using the Door Jump.
 * Kraid and Ridley do not have to be defeated to get into Tourian. If Samus lures a Reo into the room with the Stone Statues and freezes it above the acid, she can perform a difficult Bomb Jump to reach the other ledge.

Metroid II: Return of Samus

 * As stated above, Samus can roll off a ledge in Morph Ball form and unmorph, and then jump in midair, as in Metroid.
 * If Samus jumps into an enemy, she will be knocked back, and can jump higher than normal in the air. This has particular use when she is trying to climb a wall of Autracks.
 * Though it does not seem to be the case, Samus can make an indefinite Bomb Jump. She must lay a Bomb, and before it explodes, lay another one, and so forth.
 * If Samus has two Energy Tanks at the very least and the Varia Suit, she can run through the acid to reach Phase 3.
 * Samus can rapidly fire her weapons when in an enemy-filled room, to slow their movement down.

Super Metroid

 * It is possible to skip the first Torizo via Arm pumping.
 * A glitch commonly known as the "Green Gate Glitch" involves a Shutter with a green light that is on the left of the machine. Samus must jump and fire in a certain area of the Shutter to make it lift from the wrong side.
 * Samus can jump higher and farther underwater if she turns off the Gravity Suit immediately after jumping.
 * The Mockball allows for Early Super Missiles or the Ice Beam.
 * The Energy Tank in the blue part of Brinstar can be reached by using a "Damage Jump".
 * By using a quick Speed Booster charge, Samus can collect the Energy Tank in the pink portion of Brinstar much earlier and without the Gravity Suit.
 * The Wall Jump can be used to collect Power Bombs before the Grapple Beam, the Wave Beam, Spazer Beam, X-Ray Scope, reach Kraid early, and get into the Wrecked Ship without the Grapple and thus collect an early Gravity Suit.
 * Getting to Draygon without the Grapple Beam via getting the Gravity Suit early (see above) and the wall-jumping technique.
 * The Speed Booster, High Jump Boots and Power Bombs can be collected later than usual if other sequence breaks are performed, although the High Jump can also be skipped altogether.

Metroid Fusion

 * Using quick manuevers, Wall Jumps and Shinesparks, numerous Energy, Missile and Power Bomb Tanks can be obtained without the supposedly required equipment.
 * There is a secret conversation that can be watched by using a series of tricky Shinesparks in Sector 4. This would normally skip Diffusion Missiles, had the developers not locked the door to the Main Deck.

Metroid Prime

 * Using the Scan Dash glitch allows for the Space Jump Boots to be acquired before any other upgrades. This can still be performed in Metroid Prime Trilogy.
 * Samus can get into the Furnace room without the Spider Ball by using a clipping glitch, or a Ghetto Jump. When she reaches the Hall of the Elders, she can jump on a Radiation collector to reach the room's Bomb Slot, and then practice several other jumps to get to the Reflecting Pool. Once there, she can simply stand on a Stone Toad and reach the Antechamber and Ice Beam early. This is usually performed before encountering Flaahgra.
 * The Plasma Beam can be reached without the Spider Ball by either successfully performing two jumps in the Twin Fires Tunnel, or by exploiting the scan dash glitch on the Spider Ball Track in the room. Then in the Geothermal Core, several jumps can be exploited to reach Plasma Processing.
 * The Power Bomb Expansion in Security Cave can be reached using several difficult jumps. This will give Samus early Power Bombs and also enable early access to the Artifact of Spirit and other such items.
 * Early Morph Ball via Space Jump.
 * Early Gravity Suit via part of the "Early Plasma Beam" (namely passing the Twin Fires Tunnel without the Spider Ball.)
 * The Hive Mecha can be skipped via an L-Lock Spring Space Jump. This allows for Missiles to be acquired without having a battle. Alternatively, a scan dash can also be used to escape the Hive Totem, and if Samus returns, the Hive Mecha is gone, replaced by the Missile Launcher.
 * The Missile Expansion in Main Plaza's half-pipe can be reached using a Ghetto Jump, as another means of early Missiles.
 * The Gravity Suit and crashed Frigate Orpheon can be skipped via Bomb Jumping over the bars in Great Tree Hall.

Metroid: Zero Mission

 * The Screw Attack can be acquired early. First, Samus must take a secret route in the main 'bubble shaft' of Norfair. A well-executed Bomb Jump and destruction of Missile Blocks will bring Samus to the Screw Attack.
 * The Varia Suit can be collected by freezing Wavers, or by using several Bomb Jumps to reach the Varia's room. This also means it can be collected without the Power Grip.
 * The secret Missile Tank in the first long shaft of Brinstar can be collected using Wall Jumps and Bombs.
 * The Super Missile Tank near the Brinstar shaft can be reached using several Ballsparks. That in the Chozo Ruins portion of Crateria can also be reached with several Wall Jumps and Shinesparks as well.
 * As in Metroid, the Long Beam can be skipped by taking an alternate route of Fake Blocks. Skipping the Long Beam forces Samus to use Missiles in order to hit objects at long range.
 * The Wave Beam can be collected early via skipping the Ice Beam.
 * The Imago can be skipped by taking an alternate route to Ridley's Lair, or by getting early Super Missles (above).
 * It is possible to completely skip the Varia Suit, but when the Ruins Test is completed and Samus collects the fully powered suit, which activates the three Unknown Items revealed to be the Gravity Suit, Space Jump, and Plasma Beam, Samus gains the Varia Suit anyway as the new suit provides it.

Metroid Prime 2: Echoes

 * Using the infinite boost glitch, Samus can avoid losing the starting items that would normally be stolen by the Ing. Although Samus appears to have the Grapple Beam and Power Bombs stolen, she does not have them at the start of the game..
 * Using a carefully executed Bomb Jump and Screw Attack, Samus is able to completely bypass getting the keys to the Hive Temple.
 * Early Power Bombs via a series of difficult jumps in the Temple Grounds.
 * By Ghetto Jumping in the Abandoned Base, the player can enter the Torvus Bog and clear most of the game without the Dark Suit. This can still be performed in the Metroid Prime Trilogy.

Metroid Prime 3: Corruption

 * Early Spider Ball via series of glitches.
 * Early Hazard Shield via early Spider Ball. (Warning: Leads to an endgame.)

Metroid: Other M

 * An Energy Tank can be obtained earlier than usual in an area that would normally require the Speed Booster to reach in the Cryosphere by utilizing a break in an overhead Morph Ball passage and repeatedly interrupting Samus's spin jump by shooting.