R-Jump

R-jump formally refers to jumping from the ground while crouched, while holding either angle up or angle down.

A normal crouch jump puts Samus 8 pixels higher than jumping while standing. If instead angle up or angle down is held, Samus will jump 2 pixels lower than standing (so 10 pixels lower than a crouch jump).

Thus, R-jumps are not usually useful, since one usually wants to jump higher. In fact, they usually just get in the way (like making the Wrecked Ship Main Shaft clip not work).

There is one situation where they are useful: They can be used to mid-air morph in a two tile high region if suitless underwater (or underacid, or underlava). The most famous location is collecting Spring Ball without Gravity Suit.

Two-tile mid-air morph

A two tile mid-air morph is not normally possible, since Samus cannot even stand.

By using X-Ray (or a Crystal Flash, or other shenanigans), Samus can force a stand. However, even then Samus cannot mid-air morph in this height since her head sticks into the ceiling.

By jumping, pressing down, and rolling forwards, Samus can get into a crouched position while clipped three pixels into the ground. From this position, she can jump. However, since crouch jumps put Samus 8 pixels higher, this doesn't actually help: she goes straight into the ceiling with no chance to mid-air morph.

But an R-jump instead gives extra room. If Samus' initial jump velocity is low enough, a mid-air morph becomes possible.

Unfortunately, in air physics it is not possible on NTSC or PAL.

Underwater, it is possible on both NTSC and PAL. In acid physics, it is at least possible on NTSC; PAL has not been explicitly tested. (Note there is no situation in the vanilla game where this is relevant in acid physics.)

Many of these situations require near frame-perfect morphs. The most lenient is water physics on NTSC with Hi-Jump Boots unequipped. This then has a 5 frame window to press down twice. The first down press can be buffered; then there is a 4 frame window to release and re-press down.

Pause Buffer

It turns out these mid-air morphs in a two-tile region can be pause buffered. This is accomplished as follows:

- Force a stand in some way (probably using X-Ray);
- Clip into the ground in the standard way, but end with holding Down;
- Hold both Angle Up (or Down) and Down;
- Pause;
- Time a jump so you jump just before the fade-out finishes;
- Unpause;
- When the screen is completely black, hold Jump, Down, and Forwards.

If the jump was timed correctly relative to the pause, then this will work. This reduces all of the fast inputs to just timing a jump input. The frame window for jumping is as follows:

Region	Medium	Hi-Jump Boots?	Frame window
NTSC	Water	No	4
NTSC	Water	Yes	2
NTSC	Lava/acid	Either	2
NTSC	Air	Either	Impossible
PAL	Water	Either	4
PAL	Lava/acid	Yes	Untested
PAL	Lava/acid	No	Untested
PAL	Air	Either	Impossible

No Pause Buffer

If you are insane enough to attempt this without a pause buffer, here are the relevant notes.

Angle Up/Down must be released before Down is released (or at the same time). It can be released just before Jump is pressed (so Jump and Angle Up/Down are never pressed simultaneously). This gives a couple frame window for this release.

The first Down input may always be buffered, just like the pause buffer setup.

A down input is not registered at all on the frame Jump is pressed. All windows for morphing occur after this: A buffered down input must be held to the frame after jump is pressed to be registered.

The window for pressing Forwards after morphing is fairly large, especially in comparison to the other frame boundaries. Thus, it is ignored.

NTSC Water, no Hi-Jump

There is a 5 frame window to press Down twice. This makes the following (reasonable) inputs valid: D,D,D,_,D; D,D,_,D,D; D,D,_,_,D; D,_,D,D,D; D,_,_,D,D; D,_,_,_,D.

NTSC/PAL Water, Hi-Jump

Down may only be released for a single frame. There are technically three different frames that the morph can be initiated, but if the first Down press is buffered (as it should be) then only the first option is available. The valid input patterns would be: J,D,_,D; J,_,D,_,D; J,_,_,D,_,D (where J indicates the first frame Jump is pressed, and _ indicates Down is not pressed).

PAL Water, no Hi-Jump

If Down is buffered, then the following (reasonable) input patterns work: D,D,_,D; D,_,D,D; D,_,_,D.

If Down is not buffered, but is instead pressed on the second frame it will work, then the same patterns work.

If Down is not buffered, but is instead pressed on the third frame it will work, then only D,_,D will work (i.e., a perfect mid-air morph).

NTSC, Lava/Acid

Down may only be released for a single frame. There are technically two different frames that the morph can be initiated, but if the first Down press is buffered (as it should be) then only the first option is available. The valid input patterns would be: J,D,_,D; J,_,D,_,D (where J indicates the first frame Jump is pressed, and _ indicates Down is not pressed).