Revision as of 21:38, 4 December 2021

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 can be separated into four different branches: (1) Standard NMG; (2) (Crystal Flash)-less; (3) (X-Ray Glitch)-less; (4) Underflow.

There could, arguably, be more branches (e.g., disallowing both X-Ray Glitches and Crystal Flashes), but based off the below analysis this does not happen. There are two other separations: L+R and 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 don't play PAL, so I have done no actual analysis here.

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.

Standard NMG

Since this is the standard NMG perspective, this has been done before. We start with this run.

18%

This is ShinyZeni's low% RBO run. The itemset is xChargeless - Varia + 3 Energy/Reserve Tanks + Charge + Grapple.

xChargeless is a good base: We want to be able to use X-Ray glitches (like G-mode Ridley, removing the heat damage from the Ridley fight), and we want to be able to Crystal Flash (one, to generate flash suits for Maridia; two, to make Lower Norfair hell runs more feasible).

Charge is collected to kill Ridley, since we do not have enough ammo.

Grapple is collected to farm pre-Ridley, and to help in Maridia.

We now analyze which items can be cut.

Grapple

The pre-Ridley farm is done with Grapple, but it isn't actually needed. It is possible, by leading a third bug over every other farm, to positively farm Energy in pre-Ridley without Grapple.

As for Grapple's usage in Maridia, xChargeless is already a 14% category so it must be able to be cut. There is one issue: in order to do xChargeless without L+R wall jumping, one needs to have no Energy Tanks in Below Botwoon Energy Tank Room to generate a stored shinespark to then spark up Halfie Climb Room. Since this would not be possible after doing Lower Norfair, cutting Grapple would make L+R wall jumping necessary.

Charge

Charge is used on Ridley and Mother Brain 2.

If Underflow is allowed (but the later Underflow strategy is disallowed by some other means), the Mother Brain 2 can be handled.

Using the R-mode Ridley strategy (while in G-mode), it is theoretically possible to kill Ridley with only Crystal Flash ammo.

Thus, it is theoretically possible to cut Charge.

Energy/Reserve Tank

Since we have X-Ray and a Crystal Flash, we can cut a single Tank (by doing R-mode Mother Brain).

The hell runs would have to be tested to be possible, but with the Crystal Flash they should be.

Power Bomb Packs

If Crystal Flashing is not necessary during the Lower Norfair hell run (by doing a full health G-mode into Lower Norfair: The issue is making it to Ridley and back to Firefleas), then Power Bomb Packs can be cut.

First, note there is a 14% (Charge, X-Ray, Power Bomb) set. However, this requires generating max 10 Power Bomb R-mode flash suits, which require having zero Energy Tanks. Thus, these methods cannot be done (for Maridia and Zebetite Skip).

So how can this be done? Well, with max 10 Missile Zebetite kills, you do not need to Zebetite Skip. With 14% xAmmo strats in Maridia, you do not need any sparks (note this requires L+R wall jumping). In other words, this is based on 13% (Charge, X-Ray), made possible with my humanly "doable" 10 missile Zebetite strat.

Conclusion

With L+R wall jumping, you can theoretically cut 2 Power Bomb Packs and Grapple. This gives 15%, which makes sense because it is 2% higher than the 13% (Charge, X-Ray) it is now based on. Note we have now entirely removed Crystal Flashing.

Without L+R walljumping, you can theoretically cut an Energy Tank giving 17%. If Underflow is allowed (while disallowing the later strategy), then you can theoretically cut Charge as well, giving 16%.

(Crystal Flash)-less

With disallowing a Crystal Flash, but allowing X-Ray Glitches, what should the itemset be?

Well, we should G-mode into Lower Norfair. This at least requires 3 Reserve Tanks and 2 Energy Tanks. It is made a lot easier with a blue suit. Thus, we should collect X-Ray and Speed Booster, for a blue suit. This leads to an xSpeed base.

xSpeed requires L+R wall jumping (at least on NTSC: a theoretical PAL method can skip it). Thus, we can add Grapple to help in Lower Norfair and Maridia.

This leads to 17%: xSpeed - Varia + 3 Energy/Reserve Tanks + Grapple. I have tested the pieces of hell runs required for this itemset, and they are "possible". Thus, this is our base.

Now how can we cut items?

Grapple

This is the only item that can really be cut. On NTSC, cutting this will require L+R wall jumping.

On PAL, this can theoretically be avoided with a Jesuswalk Superjump. I am not aware of this being tested for human viability.

Different Base

Our base of xSpeed was just the most convenient. Speed Booster just generally helps in Lower Norfair, but specifically helps with: Entry with a blue suit to get past the Three Musketeers, and Fighting Pirate farming.

If pre-Ridley room can be reached and pre-Ridley farming initiated (using the three bug strat previously mentioned), then Fighting Pirate farming is not needed.

If Three Musketeers can be dodged while doing this hell run with at most 290 Energy, then a blue suit is not needed. Note the blue suit helps because we don't have to dodge them, but also because we can kill them and get their health drops. So dropping Speed Booster here will hurt in two ways.

If both of these can be avoided, then a different item can be added. The best choice is probably Ice, since it makes Maridia much easier.

Then, if this is possible, dropping Grapple would not require L+R wall jumping.

Speed Booster

If the Different Base strat is possible, then Speed Booster is not needed. Then, again, by following the 13% (Charge, X-Ray) strats, it is possible to simply not have an extra item.

Conclusion

If Speed Booster is not needed in Lower Norfair and L+R wall jumping is allowed, the theoretical minimum is 15%. This is based on 13% (Charge, X-Ray). This is the same as for Standard NMG analysis above, since a Crystal Flash was not used there.

If L+R wall jumping is allowed, then we can theoretically cut Grapple leading to 16%.

If Speed Booster is not needed in Lower Norfair, then we can replace it with something else (Ice) and then theoretically cut Grapple without L+R wall jumping. This would allow for 16%.

(X-Ray Glitch)-less

Without X-Ray glitches, then Lava Dive has to actually be done. Also, Ridley has to actually be fought.

For fighting Ridley, we can collect 30 Supers. Using (5/15) ammo, this is 3 extra Super Packs.

For Lava Dive, we can collect Hi-Jump.

Now what needs to be tested is if it is possible to do the Lava Dive hell run up to the GT Refill Room with 6 Tanks. I think I have tested this before, and it is possible with 3 Reserve Tanks using (not frame perfect, except maybe one for the elevator) pause abuse.

From there, I know I have tested using the Ripper 2's to farm Reserve health, and farming Supers from the Ripper 2's and Power Bombs from the Violas. I have also tested making it through Amphitheater to Firefleas.

Then, what remains is if you can make it to pre-Ridley. This is also a question for a lot of cutting items above, so we will just assume this is possible (as the above will be tested first, and then we will know limitations). We will add Grapple, for pre-Ridley farming (in case the three bug method isn't actually humanly viable).

We have no base, since we didn't actually care about other items. So pick your favorite 14% itemset that doesn't collect Gravity or X-Ray, and doesn't need L+R wall jumping. Also, we need Charge (to kill Ridley).

The only one left (on NTSC) is 14% Icebooster. This feels a little bit sketchy, since 14% Icebooster usually uses a Varia blue suit to get through Maridia. This isn't actually needed, it is just a lot easier: It is possible to carry a spikesuit through Maridia instead. This will be easier in the above case, since we also have Grapple.

Thus, our predicted low% is: Icebooster - Varia + 3 Energy/Reserve Tanks + 3 Super Packs + Grapple + Hi-Jump. This gives 21%.

Since we didn't really care about (Ice, Speed), we could instead collect two power bomb packs for a Crystal Flash. This is a GrappleChargeless base, but with Hi-Jump the L+R wall jumping isn't needed. This isn't used, so that we can simultaneously not use X-Ray Glitches or Crystal Flashes and still have the same percentage.

Now what items can we cut?

Hi-Jump

Maybe with a stored shinespark, Hi-Jump isn't needed for Lava Dive. This would have to be tested. This hell run already needed to be confirmed again, but by my memory it was incredibly tight with Hi-Jump. Thus, it may just not be possible without.

Grapple

Again, if pre-Ridley farming does not need Grapple, we can theoretically cut this.

Ice or Speed

On PAL, we could instead use an Iceboots or Speedboots base to cut one of these. This would require keeping Hi-Jump. But it does give us 20% for free on PAL, since our above analysis didn't actually use Ice or Speed in Lower Norfair.

Super Packs

Our Super Packs are used on Ridley. If we could kill Ridley a different way sufficiently quickly (I know 30 Supers works with 6 Tanks, with getting back to pre-Ridley farming), then we could lower the percentage.

The only thing that even seems remotely viable is cutting 2 Super Packs and replacing with Wave Beam. This cuts a percentage, and then requires doing 5 xFactors on Ridley. Good luck.

10 Missile Zebetites

A lot of the analysis for 14% categories depends upon Zebetite Skip being required. If 10 Missile Zebetites are allowed, then maybe something can be cut.

In this case, nothing jumps out at me. But maybe I am missing something since I am just typing up some quick notes right now.

Conclusion

On NTSC, it seems like the best case is to theoretically cut Hi-Jump, Grapple, and 2 Super Packs, but then add Wave. This gives 18%.

On PAL, it seems best to theoretically cut Speed, Grapple, and 2 Super Packs, but then add Wave. This gives 18% as well, but Lava Dive should be nicer.

Thus, I think 18% is a lower bound, while not allowing for X-Ray Glitches (and also Crystal Flashes, but this is a by-product: I just think allowing Crystal Flashes doesn't lower percentage). I should re-consider this, since maybe I am wrong.

Also, if the Lower Norfair hell runs for the above sections prove impossible, then a Crystal Flash may be needed. This is future work.

Underflow

It is possible to Underflow at Draygon, use Draygon to get pushed through the door, and then escape with the spark from Underflowing.

This gives Underflown ammo while Draygon is still alive.

In my opinion, this satisfies the definition of RBO but not the spirit of RBO. Yes, we didn't kill Draygon, but we did enter her room. But rather than debate about this not being allowed in RBO, I will just analyze how it changes things.

I have fully tested that it is possible to get to Draygon (under 14% Chargelice conditions, which seemed easiest), underflow, and escape.

After this, you want to now use your nigh-infinite ammo to Crystal Flash and get through Lower Norfair with no other items. Well, you can't Crystal Flash with ammo greater than 32768, and you now have about 65535 of every ammo type. Thus, you have to spend like 12 hours wasting ammo, to get each below 32768.

I have tested this as well. I then went through Lower Norfair with nigh-infinite Crystal Flashes and only three Tanks. I killed Ridley (using 30 Supers in 3 Tanks: Crystal Flashing during Ridley is deadly), and escaped. I then finished the rest of the game, confirming that 14% RBO is possible.

However, this action of spending 12 hours of wasting ammo (which assumes fairly optimal ammo wasting) takes forever. I did this across weeks, if not months. I would load up the save file when watching something else, and just slowly waste ammo. Thus, this is definitely not viable.

In conclusion: With Underflow allowed (and visiting Draygon without killing her allowed), 14% RBO is possible but extremely stupid. The possible itemsets are Chargelice, xChargeless, GrappleChargeless (L+R), and Pb-Pb (L+R).

Conclusion

The above analyzes everything fairly well. The (X-Ray Glitch)-less section needs to be fleshed out better, but this will come after completing the sections above it (since the hell runs are a subset of [X-Ray Glitch]-less). It suggests the following theoretical minimums, that require quite a bit of extra testing:

THEORETICAL:

Underflow (and visiting Draygon) allowed: 14%

X-Ray Glitches allowed (Crystal Flashes may be banned or not): 15%

X-Ray Glitches allowed, but L+R banned (Crystal Flashes may be banned or not): 16%

X-Ray Glitches banned (Crystal Flashing may be banned or not): 18%

The current state of my testing is as follows (note these are TESTED, but not necessarily actually completed with a RUN, so I may have made a mistake somewhere and things may not be actually viable):

TESTED, BUT NOT ACTUALLY COMPLETED:

Underflow (and visiting Draygon) allowed: 14%

X-Ray Glitches allowed, but L+R banned (Crystal Flashes may be banned or not): 18% [this is ShinyZeni's run, so is the only one that is truly confirmed]

X-Ray Glitches allowed, with L+R (Crystal Flashes may be banned or not): 17%

Crystal Flashes Banned (X-Ray Glitches Allowed): 17% [this is the itemset I took as the base in the above: This was my base, because I tested all pieces]

X-Ray Glitches banned (Crystal Flashing may be banned or not): 21% [this is not really fully tested: From memory, I think I tested all the pieces, but there are some gaps in my notes]

I want to flesh this stuff out better, and get some clips to show the strategies involved. In short, I would like to confirm the theoretical lowest percentage as "possible" (even if quite far from "viable"). The above is a placeholder, since it was just stuck in my head this morning.