Part 8: Sketch Glitch
Today, we’re going to be exploring the infamous sketch bug. The glitch is easy to perform and creates strange yet beneficial effects, causing it to be one of the most famous glitches in gaming history, standing strong among Missingo and the black beam in Super Metroid. We’re going to be taking an in-depth look at the sketch glitch – why it happens, what causes it, and most importantly the effects it causes.
I should warn you: The Sketch Glitch is considered to be moderately dangerous. Chances are when you do the glitch, nothing out of the ordinary will happen to your cartridge aside from the normal graphical glitches and changes to your item list. But, people have reported save files getting deleted completely and even cartridges becoming unplayable. Try it at your own risk.
Because of the nature of the glitch, this update and the one after is going to be hybrid – a subtitled VLP and a
Too lazy to read words? You can skip straight to the video by clicking here. You can still get the gist of what's going on, though not as detailed as you'll get from reading the thread. 
The glitch in its simplest form works like this:
1.) Turn an enemy invisible
2.) Sketch that mofo
3.) Watch the game implode on itself
This causes a whole bunch of strange things to happen. Firstly, your battle screen will become really messed up. Either the screen will start flickering and your game will crash, the game will straight-up freeze, or you’ll be left in the situation shown above. You can actually battle here if you wanted, but chances are you can’t target an enemy, so running away or using a Warp Stone are your best options.
More importantly, your inventory is just consumed and replaced with a whole bunch of items. Sure, you might lose out on some cool stuff, but you gain things like 255 Illuminas or Atma Weapons, and enough weapons and armor to sell off to last you the rest of the game.
The real question is, why the hell does this happen? First, it’s important that you know how the glitch is triggered. It goes far beyond “invisible, sketch, implode”.
1.) First, it needs to happen on the 1.0 version of the cartridge. The US got a 1.1 version released at some point that fixed the bug, so it’s impossible without a Game Genie. Using the Game Genie code “C2F5E680 will revert this fix and allow it to work.
2.) The character in the first slot needs the same aiming byte as Mute in the 28th spell slot in your in-battle magic menu. What I mean by “the same aiming byte” is a spell with the same properties as mute, namely that it cannot be multi-targeted and defaults to the enemy. Another spell similar would be Berserk. To get it to the 28th slot, you can rearrange your spells in the config menu. A full battle list will use Battle Menu 3, a semi-complete one may use a different battle menu because the game compresses your spell list. With certain spell combinations it may be impossible to do this until you require more.
3.) There are 3 main variations on the effects of the sketch glitch, and that’s whether or not you’re able to cast Mute when entering battle or during battle. The way to trigger this is through the “Imp” status. The three variations are:
-Never being in Imp Status
-Beginning in Imp Status
-Applying Imp Status mid Battle
By doing these various steps you can get entirely different effects. However, the biggest factor in what will happen to you is the Mould of the enemy. Moulds go from 00-15, and each Mould will produce an entirely different effect from the next. A loose definition of Mould is the formation of the enemy. A more correct definition would be what the enemy formation is placed. Mould 00, for example, will not always be 3 small enemies in a triangle formation. The specifics for which enemies go into which Mould seem to be random, though generally small enemies, big enemies, and bosses have common Moulds. Moulds cause the most random glitches, and that’s what we’re going to explore throughout the video.
4.) Don’t cast magic with the first character. For some reason this can mess with the glitch, nobody knows why.
5.) Sketch against any enemy that you will “miss”. Sketching an invisible enemy is the most popular, however really any miss will do. Sketching high-level monsters or Gau when he returns from the veldt are two other popular ways, but with (un)luck it can happen completely randomly on a weak enemy.
That should be it, and the glitch will trigger, sending your inventory showering with dirks and your characters turned into garbled messes.
One of the biggest misconceptions with this glitch is that it’s 100% random. Not true – there isn’t much random about this glitch. The graphics are sometimes changed by untrackable variables, however the effects (AKA ‘will it freeze’) and the items you obtain will always be exactly the same across all cartridges.
I’m not going to bore you all with the technical details. In a nutshell, the game will attempt to load bad sprite data when a sketch is missed. However, the game needs some pointer as to where to load the monster data. Normally the pointer will extract the data needed, but there's an error in the coding. When the 28th slot of the Magic Menu is a single aiming byte, the pointer points to some obscure line of code buried somewhere. The game, sepcifically loads from these 4 segments of code:
7E20FE: Spell Index Number
7E20FF: Who knows? Determines spell availability
7E2100: Spell aiming
7E2101: MP cost
The middle two are the only ones that matter. The 20FF is not completely understood, but it can be manipulated by the Imp status effect. Normally when the game tries to load from these two locations nothing out of the ordinary will happen. But when the Spell Aiming Byte is set to the one mute is assigned, the game will load "sprite data" (hint: it's probably not sprite data) from and obscure place and the game will go completely bonkers.
Everything in an SNES cartridge is loaded through segments of code. Music is certain lines of code, map sheets are certain lines of code, palettes are certain lines of code, and most importantly monster sprites are certain lines of code. So what the game may be loading is the Veldt theme song, Celes’s sprite, Terra’s palette. Nobody knows. It’s not worthwhile to determine what data the game is trying to read, because the game is essentially flipping over their office desk and screaming “fuck it, just load whatever”.
See, games back then were traditionally designed without failsafes. Due to memory and space issues, programmers had to work with what space was available. FF6 is a huge detailed game, they had to do their best to conserve space on the cartridge. Saving space meant no failsafes. Whenever something big slipped through the cracks – either due to shoddy programming (the sketch glitch) or something they would never expect (the airship glitch), there was no signal that said “UH OH THE GAME BROKE, BETTER RESTART THIS BEFORE I EXPLODE”. The game just, well, exploded. The entire Let’s Break Pokemon Blue shows this concept off perfectly.
For a more detailed explanation of the glitch, read Master ZED’s Sketch Bug Guide.
Now that that huge “history and explanation of this glitch” mini-FaQ is over, we can get to the real content of this LP: watching the game explode.
Important items gathered from different Moulds:
Mould 00, No Imp
Illumina (x381)
Economizer (x255)
Mould 00, Imp Before Battle
Economizer (x73)
Mould 01, No Imp:
Gem Box (x255)
Economizer (x143)
Mould 01, Imp Before Battle
Excalibur (x255)
Atma Weapon (x255)
Tempest (x28)
Rainbow Brush (x255)
Mould 01, Imp During Battle
Flame Shield (x255)
Sword Breaker (like, over 1000)
Mould 07, No Imp
Marvel Shoes (x32)
Excalibur (x16)
Illumina (x255)
Mould 07, Imp Before Battle
Gem Box (x136)
Atma Weapon (x7)
Flame Shield (x52)
Illumina (x75)
Megalixer (x255)
Mould 07, Imp During Battle
Illumina (x255)
Paladin Shield (x202)
Ribbon (x255)
Aside from these items, you also acquire a lot of decent equipment, or rare equipment that isn't that great that sells for a lot. As a general rule, sketch once and unload your inventory for nearly unlimited gold.
Next Time: More Sketch Glitches, but without a huge subtitled video segment. Returning to primarily Screenshot format.