View source for Bobbob's notes on low% RBO

These are some preliminary notes, since I have it stuck in my head right now. I'll transfer my full notes here at some point.

Low% RBO has a number of considerations:  [[Underflow]], [[X-Ray Scope Glitches|X-Ray Glitches]], [[Crystal Flash|Crystal Flashing]], [[L+R Walljumping]], and NTSC/PAL.

Heat damage is slower on PAL, so hell runs are easier. Thus, it is always easier to do the route on PAL, and sometimes it may be possible to cut an item in PAL but not NTSC. I am unsure about how much easier extreme Ridley fights are in PAL due to this, since charging a beam still takes 60 frames, but Ridley's AI is also easier to avoid in PAL due to being slower.

L+R wall jumping can help a lot in Maridia. This allows one to focus more on Lower Norfair, and thus can help cut items.

Note that, in low% RBO, it is standard to collect 6 (Energy/Reserve) Tanks and skip Varia. Thus, the base percentage in low% RBO is 16%. Beating 16% will require having fewer than 6 Tanks. Note that, with standard strategies, to collect fewer than 6 Tanks would require collecting at most 4 Tanks:  If you collect 5 Tanks, then you need to collect Varia to survive Mother Brain's Rainbow Beam, which still totals 6 items. Thus, at the 6 Tank boundary, it is usually required to cut 2 Tanks to save an additional percentage.

There would be an exception for [[14% xChargeless|options that collect X-Ray and Crystal Flash ammo]], since [[R-Mode#R-mode Mother Brain|R-mode]] would allow completing the Mother Brain fight with only five tanks.

=Basic Item Collection=

The first thing to consider is if all desirable items can actually be collected.

All of the major items outside of Maridia are readily available. The Maridia majors also aren't very helpful, so that's fine.

For Energy Tanks, at least Blue Brinstar Energy Tank, Terminator Energy Tank, Gauntlet Energy Tank, Etecoons Energy Tank, Wavegate Energy Tank, Hi-Jump Energy Tank, and Crocomire Energy Tank are readily available. This is already 7 tanks (without any Reserves), so it's unlikely that more would be needed.

There are more than enough Missile Packs.

For low% purposes, I can't see needing more three Power Bomb Packs which is already settled by Etecoons Power Bombs, Alpha Power Bombs, and Beta Power Bombs.

==Super Missiles==

For Supers, there are Early Supers, Etecoons Supers, and Spore Spawn Supers as the readily available ones. This is good enough for minimal ammo, of 5/15.

If more ammo is needed, then maybe more majors are needed to collect them:

*GT Supers:  This should actually be readily available if needed. If entering from the front, then you are most likely stopping by the energy refill and then this pack is right there. The GT fight itself shouldn't add conditions (although may be obnoxious). If entering from the back, then you are using G-mode so should just handle Ridley with G-mode and thus don't need the extra supers.

*Crateria Supers:  Needs Speed Booster, Crystal Flash, or X-Ray.

*Crab Supers:  Whatever method you use to get through Maridia should be able to acquire this item, so this should also be available.

*Watering Hole Supers:  This needs some way to get up [[Pseudo Plasma Spark Room]]. Most itemsets that get through Maridia should be able to do this, but it might also just be really annoying.

*Aqueduct Supers:  This needs X-Ray or an ability to have a spark in [[Aqueduct]]. The latter is a confusing set of conditions, but, again, if you can comfortable get through Maridia and can generate a shinespark then this is probably accessible. It is just a question of how annoying it is.

Based off these words, we can see that basically any itemset that wants them will have 25 Supers available:  Crab Supers and GT Supers at least. To complete the analysis, we note pre-Botwoon must be solved. This is solved either by Ice Clip, a shinespark, a CF clip, or R-mode. The last three options can get Crateria Supers; the first can get Watering Hole Supers. Thus, any low% RBO itemset can collect 30 Supers.

==Reserve Tanks==

Note Reserve Tanks are more useful than Energy Tanks, due to [[Pause Abuse#Reserve Abuse|Reserve Abuse]]. Being a hot commodity, collecting the most we can should help.

Two are readily available:  Brinstar Reserve and Norfair Reserve. One is not available:  Wrecked Ship Reserve.

This leaves Maridia Reserve. Again, since Maridia must be solved at some point, we can get to Aqueduct. Then this Reserve can be gotten with either Hi-Jump or [[L+R Walljumping]].

If neither of these are accessible, it is possible to use a shinespark (to break the surface of the water) and a [[Sponge Bath]]-esque bomb jump (to break the surface of the water again) to get to this item.

It is also technically possible with [[G-Mode]], by using two-wall underwater walljumps and then using the bomb jump.

So it's possible for this Reserve to be inaccessible. But we can always have at least two, and usually three.

=Maridia Routing=

We now consider our options for getting through Maridia. For the most part, this can be done by looking at the [[14%]] options and removing any that collect Gravity Suit. Also, the [[Underflow]] options may look appealing, but since Ridley needs to be killed before Draygon they are not as helpful as one might think (except for the Underflow route, see below).

This leaves (currently):  xIce, xPb, xBoots, xGrapple, xSpeed, xAmmo, xCharge, xChargeless, Icebooster, Grapplebooster, Chargelice, GrappleChargeless, Peebs, SuperChargeless, Iceboots (PAL), and Speedboots (PAL).

In short, these are the itemsets that one should consider the "base" of there run. From here, tweaks should be made to make it possible with an RBO perspective.

As a remark, Icebooster is possible as a base. Usually, [[14% Icebooster]] is done with a blue suit generated from Varia. This is not needed:  A spikesuit may be used instead. In fact, my current pb for this category does this.

=Current Run=

The current record, done by ShinyZeni, is an 18% run. It uses an xChargeless base, with 6 Tanks and no Varia, and additionally collects Charge and Grapple. Charge is collected to kill Ridley (as any Underflow-less route must do to be low%), and Grapple is used to help with Lower Norfair farming as well as make Maridia possible without [[L+R Walljumping]] (note although [[14% xChargeless]] doesn't require L+R Walljumping, it avoids it by using an R-mode CF Suit that requires having zero energy tanks:  Since one would have more than zero energy tanks when going to kill Draygon, this is not an option).

Now we consider potential improvements to this route.

==Energy/Reserve Tank==

By using R-mode Mother Brain, that fight can be done with only 5 Tanks. If the rest of Lower Norfair can be done with only 5 Tanks (most likely possible, due to having a Crystal Flash), this would allow cutting an item.

==Grapple==

Grapple can be avoided with L+R Walljumping. On PAL, it should be possible to avoid even without L+R Walljumping, by using a Jesuswalk Superjump. On NTSC, to avoid it would require the Mt. Everest Slopespark.

==Conclusions==

It seems likely that 17% is possible, by cutting a tank. Further cutting down to 16% (most likely with [[L+R Walljumping]]) would be quite difficult.

=Entering From the Front:  X-Ray-less=

Note that, with X-Ray, entering from the back is always possible:  Using a full health G-mode with 2+3 Tanks, you can make it to Firefleas and then farm to full. Thus, any X-Ray route could just enter the back and not have to deal with lava dive.

So, when considering the front entrance, we may as well eliminate X-Ray as an item and try to live without.

Looking at the available 14% categories with this restriction, an Icebooster base seems best:  It has Ice (to increase damage to Ridley and make Maridia easier), as well as Speed Booster (to help with lava dive, and make the third Reserve accessible).

We now analyze the issues. Note our base is 16%, with 3+3 Tanks and no Varia.

==Zebetites==

Not an issue, since we can Zebetite skip. Thus, we can have 5/15 ammo.

==Lava Dive==

I have tested the lava dive hell run (to the GT refill) with a spikesuit and 6 Energy Tanks, and it is just barely possible. Since this run would have 3+3 Tanks, it wouldn't be nearly as tight. In fact, my notes suggest that 4+1 Tanks and 1+2 Tanks are both possible (although extremely tight), so a 3+3 run should be learnable.

==GT Refilling==

It is possible to use the Viola to fill Power Bombs, the Ripper 2's to fill Supers, and the Ripper 2's (when full on Supers killing them with power bombs) to fill Reserves. My notes suggest this requires at least 2 Energy Tanks, so again with 3 Energy Tanks this should be possible.

In the end, you will be short one power bomb, to farm the Ripper 2's one last time.

==Getting to Firefleas==

I have tested the hell run to Firefleas from GT refill with no additional items, on 6 Energy Tanks. So, again, it should be quite feasible with 3+3 Tanks.

Unfortunately, Speed Booster does not help much here, and I'm sure my test did the WRITG walljump. So...good luck.

==Firefleas Farming==

We can arrive with full supers. Even if we can't, we could do Namihe farming to fill them: It just takes forever.

Other than that, farming everything else here is standard.

==Getting to pre-Ridley==

I, unfortunately, do not have detailed notes on this hell run yet. I only have my basic notes from years back, which state it to be possible. Who knows if I actually tested it with 6 Energy Tanks, or 3+3 Tanks.

But either way, my notes also indicate that with Speed Booster it is possible to positively farm the Ninja Pirates. Thus, even if this hell run is stupidly tight, Speed Booster will come in and help.

==pre-Ridley Farming==

Normally, this is done with Grapple. On PAL, it is just straight up possible without.

On NTSC, it is also possible without. Every other farm, you lead a third bug over to the farming spot to be killed simultaneously with the other two bugs. I remember it being incredibly annoying, but possible.

==Ridley==

With the pre-Ridley farming strat mentioned above, you can enter the Ridley fight with 44 damage and full ammo.

Unfortunately, 5/15/5 ammo with Charge+Ice requires 73 Charge shots. Basic math suggests this will take 1385 heat damage. My basic computations on reserve abuse suggests that each tank is worth 171 energy, if used near optimally. Thus, we have an effective energy of 868. I don't see humans being able to frame perfect [[Pause Abuse]] that difference.

===Super fight===

Thus, something must be added. The obvious thing to add is two super packs, giving 5/25/5 ammo. With this, only 6 Charge shots are needed, reducing heat damage of this fight to 414. Adding in (optimal) pre- and post-Ridley damage, and damage before entering, the fight requires 648 energy. This assumes an absolutely perfect fight in many regards (e.g., no turning around while charging your beam), but in some other regards it is imperfect (e.g., your first shot on Ridley is free, not needing a cooldown).

Thus, I tested this fight with 699 at the start (so without the 44 damage I should have had). I managed it with one frame perfect pause waiting for drops. Thus, with Reserve Tanks, the fight should be readily possible. The RNG also shouldn't be that bad, since it's a fast fight with 25 Supers.

Note my fight also used power bombs. My notes now suggest it is technically faster to use ice shields, and 8 Charge shots. I didn't actually try this fight, but no matter what it should be better to open with an ice shield (which does not increase the number of Charge shots needed, since Ridley had 40 extra damage dealt).

===Wave fight===

Instead, you could add just one item of Wave Beam and use x-factors.

With 5/15/5 ammo, this would then require 14 Charge shots if every x-factor particle hit. Again, my basic math suggests this fight requires 688 energy total for everything.

However, again, this assumes a perfect fight:  No time needed to set up x-factors, always shooting, etc.

I tested this fight with 4+2 Tanks (I was hoping the third Reserve could be avoided, since it's a long trek), and did manage it. However, I learned that x-factors on Ridley are a severe pain after the third. Either some serious work needs to be put in to find the correct manipulations and timing, or you could just bash your head against the wall to get the RNG you want.

==post-Ridley farming==

The above Ridley energy requirements went until drops. You'll most likely be health bombed, so these can then sustain you to get back to bug farming.

==Hell run back to Firefleas==

This, in theory, should be similar to the hell run to get down here. Again, I don't have good notes. Again, Speed Booster should ensure it is possible.

==Escaping Lower Norfair==

This is a really short hell run. In fact, I have confirmed that the hell run to escape Firefleas back to Bubble Mountain is possible with 1 Reserve + 1 Crystal Flash. Thus it should be trivial with 3+3 Tanks. Annoying with dodging the Three Musketeers, but the post-Ridley save should make this possible to grind out.

Note you'll want to know the minimum health to get from the Ridley save to Firefleas, so you know if you should save or not.

==Conclusions==

The above analysis says:

*17% is the minimum humanly, adding Wave;

*18% is more reasonable, adding 2 Super Packs;

*with 3 Super Packs, Ridley would become much easier leaving only the hell runs to contend with;

*with Grapple, the most obnoxious part of the hell runs in my opinion (pre-Ridley farming) would become much easier.

=Entering from the Back:  All the X-Ray Glitches=

We now consider a route for using X-Ray. The base will be [[13% xCharge]], which requires [[L+R Walljumping]]. To avoid this, one of Ice, Hi-Jump Boots, or Grapple should probably be added; other things may work, but it'd probably be harder than figuring out how to get L+R Walljumping to work on whatever you are using (yes, I am including butchering an original SNES controller to make L+R Walljumping possible on console).

Note our minimal consideration here is actually only 5 Tanks, since R-mode on Mother Brain may allow removing one if you have a Crystal Flash.

==Getting to Firefleas==

With 2+3 Tanks, it is possible to get to Firefleas without a Crystal Flash. It does not appear feasible with fewer Tanks.

This means, in order to enter, the Maridia Reserve must be collected, or a Crystal Flash must be used.

As remarked previously, technically G-mode from Aqueduct is sufficient to collect the Maridia Reserve, although extremely annoying. Thus, for purposes of figuring out the minimum, this will be ignored. However, note you should consider this if routing without L+R Walljumping.

==Getting to pre-Ridley==

Again, my notes on this are very minimal. Thus, I don't know if this is possible on 2+3 Tanks, or even really if 3+3 Tanks is feasible (before I depended upon Speed Booster to know it was feasible).

With a Crystal Flash, it should be trivial.

==pre-Ridley Farming==

This would be the same as without X-Ray. But it is also mostly pointless due to:

==Ridley==

Use G-mode on Ridley to not have heat damage.

You still need enough ammo to be able to kill Ridley. Charge would be cheapest, hence our 13% xCharge base.

Note, as in the current run, with a Crystal Flash this is trivial.

==post-Ridley farming==

Again, this is technially possible.

==Getting back to Firefleas==

Again, I don't really know if this is feasible on 2+3 Tanks. With a Crystal Flash, it should be.

==Escaping==

This is simple.

==Conclusions==

*15% with L+R walljumping is possible, if the hell run to pre-Ridley and the hell run back to Firefleas can be done.

*16% without L+R walljumping is possible with a similar condition.

*16% with L+R walljumping should be possible:  An xChargeless base, so a Crystal Flash can be used for any of the questionable hell runs. This also makes Ridley not completely terrible. This is basically ShinyZeni's route, but made terrible by removing all the helpful items, so is what was mentioned previously.

=Underflow=

It is possible to Underflow at Draygon, and escape the room without killing her. I have tested this fully, under [[14% Chargelice]] conditions.

From here, you can use 32768 of every ammo type to be able to Crystal Flash again. You then have nigh-infinite Crystal Flashes, which allows hell running Lower Norfair and killing Ridley (using 30 Supers) with only three tanks.

Thus, this makes 14% possible.

This has two questionable aspects:  (1) Some people don't like Underflow; (2) Visiting Draygon before killing Ridley could be seen as not in the spirit of RBO.

Note if [[13%]] IcePb is done RTA, this would also be applicable here allowing 13% RBO.

=Total Conclusions=

From the above, we have the following:

*18%:  Minimum achieved (on NTSC without L+R Walljumping), using X-Ray and Crystal Flashes;

*17%:  Theoretical minimum (on NTSC) without L+R Walljumping, X-Ray, or Crystal Flashes;

*16%:  Theoretical minimum (on NTSC) without L+R Walljumping or Crystal Flashes (but with [[G-Mode]]);

*15%:  Theoretical minimum (on NTSC) without Crystal Flashes (but with [[G-Mode]] and [[L+R Walljumping]];

*14%:  Theoertical minimum (on NTSC) with Underflow (but without X-Ray glitches or L+R Walljumping);

*13%:  Extra-theoretical minimum (on NTSC) with Underflow (but without X-Ray glitches or L+R Walljumping);

*13%:  TAS minimum (on NTSC), without X-Ray or Crystal Flashes (as far as I know, TAS doesn't actually need L+R to break the surface of the water, so "L+R Walljumping" is basically a useless consideration for TAS).

Note in the above list, when I say something is possible without Crystal Flashes this is more of a fun coincidence than a requirement:  Allowing Crystal Flashes doesn't allow for lowering the percentage, except possibly with underflow.