Megaman Zero RNG Manipulation

Notes / Guide to RNG manipulation in Megaman Zero by Flameberger.


Introduction:
The RNG in Megaman Zero 1 is surprisingly easy to manipulate in most stages. The RNG seed is always reset at the beginning of a stage, I.E. your actions in previous stages will never affect the RNG in following stages. Furthermore the seed will only be affected by events that have randomness in them, these are relatively limited and easily controlled in most stages.

General "events" which affect RNG:
- Shooting a wall with the buster.
	This is because there is a random selection of animations which play when the shot hits a wall, shooting
	enemies has a different, not random, animation. Shooting walls a specific number of times is an easy way
	to get desired RNG, though it is only a good option in stages where you have the buster equipped already.
- Killing enemies.
	There are two reasons this is a thing. First is that enemies can randomly drop health or energy when
	killed.	Second is that many enemies have multiple death animations, one of which is selected when needed.
	Sometimes the attack used to kill an enemy changes their death animation and can thus affect the RNG, for
	example	charge attacks will typically affect the RNG in different ways than regular saber attacks.

	Changing which enemies to kill is the most common form of deliberate RNG manipulation as it is a good
	option even when the buster is not equipped. Depending on how rare the desired RNG is it can be difficult
	to find	a route which produces the desired pattern.
- Sliding down walls.
	The smoke that is kicked up from Zero's feet when sliding down walls has some randomness in position.
	Walljumping is fine because no smoke in generated if you are fast enough. I have not tried deliberately
	sliding down walls to manipulate RNG because I think it would be too precise of timing and because it would
	be slow.
- Cyber Elves
	These are tricky little buggers. I'm not sure if it is random movement or random visual affects (or both),
	but having Cyber Elves flying around on screen will generate randomness. In stages where RNG manipulation
	is used it is best to avoid setting loose any Cyber Elves.
- A.I. Decisions
	Certain enemies will make random choices about what they are going to do. This can generate randomness in
	situations where you allow enemies to make more decisions than they normally do, by going slow for example.
- Other
	There are a number of additional things that can generate randomness, some unavoidable. These will be covered
	in the following sections detailing individual stages.

01 - Intro

The golem has two attacks he can do, RNG manipulation is straightforward. Kill the same enemies every run, do not
shoot the walls unless deliberately done for manipulation. In my All Missions route I kill the first pantheon in the stage and nothing else, causing the Golem to aim his attack up.

02 - Disposal Center

I am uncertain if Aztec Falcon's patterns are random or if they are based entirely on your movement during the fight. Furthermore I think the wind generators kick up random smoke that would make RNG manipulation impractical. Neither of these things have been tested sufficiently.

03 - Retrieve Data

Be careful not to let yourself slide down the wall when climbing in the beginning. Of particular note in this stage is some very strange behavior from Maha. His pattern seems to be affected by whether or not you dash into the boss room. In situations where you dash jump and hit his door before landing this affect to his behavior is avoided. Doing that adds the risk of sliding down the door if your positioning is bad, I prefer to deliberately dash along the ground into the door every time for consistency. It is important to note that Maha is very reactive to your positioning during the fight, so even with the same RNG every time you may get different patterns depending on how you move.

04 - Destroy Train

the mini-boss can be easily manipulated for a perfect pattern. Killing no enemies during the stage and shooting two buster shots into the wall will cause it to fire projectiles aimed up for it's first attack every time. The Pantheon Core has no randomness so further RNG manipulation is unneeded so long as you don't care about item drops.

05 - Occupy Factory

No RNG manipulation is needed.

06 - Find Shuttle

Anubis is the Egyptian god of RNG, manipulating him consistently would be an impressive feat and a major improvement to the route. The nature of his stage and his fight present major hurdles. Killing enough vultures will cause a cyber elf to drop, so avoid doing that, since the cyber elf is desired I recommend getting it on the way back. There are platforms in the stage which fall when you stand on them, this generates randomness so any manipulation of the stage necessitates being consistent in which platforms are knocked down. Furthermore the tornado generators that kick up rocks also seem to be a source of randomness, the details are unknown to me but these are the main hurdle within the stage, I think if you are consistent enough in how quickly you kill them then the RNG manipulation can be preserved, but it seems challenging.

Anubis himself is a big problem, every time a cycle is completed his weapon and any zombies he has summoned will fall into the sand. Both of these events seem to generate randomness based on when they happen, making it very difficult to maintain RNG manipulation throughout the fight. I will put more time into this stage at some point, hopefully these difficulties can be overcome.

07 - Giant Mechanilloid

There are some wonky things about manipulating his pattern, but as his pattern is not important for most routes it isn't a big deal. In particular there seems to be a time element to the RNG manipulation, if you waste too much time getting to the trigger that starts the fight it will affect the pattern, also if buster shots are going to be used for the manipulation they seem to need to be fired at consistent times as well.

08 - Defend Factory

As the boss of this stage is located at the very beginning, RNG manipulation is foolproof. There is an invisible wall to the left at the very beginning of the stage that can be shot once to get a very good Phantom pattern.

09 - Find Hidden Base

Not much out of the ordinary here. I've found that being detected by enemies inside the base will usually mess up my RNG manipulation, probably because of the summoned enemies.

10 - Rescue Colbor

No RNG manipulation needed.

11 - Duel in the Desert

The section where enemies are dropped from the transport helicopter can generate randomness, I've found that so long as I get through quickly it isnt a problem. Other than that nothing out of the ordinary.

12 - Stahp the Hacking

No RNG manipulation needed.

13 - Base
Nothing out of the ordinary, be careful not to slide down walls when falling down or climbing up the elevator shaft.

14 - Neo Arcadia Shrine
The pattern of the dogs in the beginning of the stage, i.e. whether or not they jump at you, can be controlled with RNG manipulation depending on which enemies you kill and whether or not you jump in certain areas. I have not succeeded in manipulating the Sword Dancer's pattern due to the Cyber Elf that gets dropped by the Pantheon Aces. If someone could consistently grab the elf or get it off screen in around the same amount of time then it should be possible to manipulate him.

15 - Neo Arcadia Tower
There's some weird stuff with the helicopter things in this stage. They seem particularly sensitive to how you kill them, I've found charge saber attacks to be the safest way of bringing them down, just make sure your positioning is somewhat consistent. The trickiest part is that they randomly chose between two different attacks, this can be a problem if you cause them to be loaded earlier by say, jumping. To avoid the problem just don't jump while riding the elevator in situations where you are close to seeing helicopter enemies, just stay on the elevator until they are in sight.

16 - Neo Arcadia Core
Routing this stage is where it all began. It can be pretty challenging to keep the RNG going as long as possible in here but it is very rewarding. The platforming sections between the boss rooms are pretty straightforward, so I'll focus on how to kill the bosses without causing randomization.

For almost every boss it is important to end the fight with specific timing. Every time the boss selects the next attack it will do that can change your RNG for the following fights, avoid boss strats that end the fight around the same time as when the boss choses it's next move because if you are slower or faster than usual you will get different patterns. Instead try to end the fight during the middle of one of it's attacks.

 - Herculious -
If he has his chains attached to wall when you end the fight their destruction will affect the RNG.

 - Blizzack -
Do not end the fight during his beam attack, wait til it ends.

 - Anubis -
Anubis is still tricky but with charge attacks it's more manageable. Use a regular attack at the start of the fight so he flies to the other side, start charging. Do not hit him with the charge attack until after he has grabbed his weapon, and make sure to always hit him with the same timing after he grabs it, I normally hit him a moment (0.25 seconds ish) after he grabs it. The side you are on when he finishes his pillars cycle will affect the RNG. Make sure to charge an attack during the pillars, when Anubis becomes vulnerable hit him and both of his zombies with the charge attack. If the zombies are not killed like this they will generate randomness.

 - Maha -
Nothing noteworthy here, just fight him the same way every time

 - Fefnir -
Also pretty straightforward

 - Leviathan -
Her attack patterns are not random, but she will mess up your manipulation unless you are very careful. However, attempting to keep the manipulation going through Leviathan is, as far as I'm aware, pointless. See Phantom for why.

 - Harpuia -
His pattern is not random and it seems like he won't affect your RNG manipulation in any way.

 - Phantom -
After defeating phantom he shakes randomly until you finish talking to him. This means that unless you can get through the dialogue with very consistent timing (2-4 frame windows from my tests) it is impossible to keep the RNG manipulation going after Phantom.

You can put Harpuia anywhere in the sequence since he has no impact on the RNG that I've found, but just in case I normally put him and Leviathan at the end because there is no benefit to facing them with the RNG manipulation intact. Fefnir must be before Phantom though if you want a consistant Fefnir fight.

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That's all I've got for now. There is more work to be done on this that will hopefuly allow even more of the game's RNG to be eliminated. Feel free to message me on Twitch with any questions or comments.

 ~ Flameberger