Yu-Gi-Oh! Dark Duel Stories RNG manipulation

UPDATE: This manip is inconsistent for reasons I don't understand. I have a proof of concept that it works in runs (manipping the same Tristan duel across multiple fresh save files), but it doesn't seem usable until someone digs into the code and figures out why it's inconsistent. I've reached out to Froggy25 for assistance, and I'll update this paste with any discoveries.

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This works on Gambatte-Speedrun, and Ninja has gotten identical duels on console, so it probably works there too (although as with Pokemon, the RNG might differ on console).

The RNG in Yu-Gi-Oh! Dark Duel Stories starts at 0 when you hard reset, and it does not advance until you've loaded your save file (so after you hit CONTINUE on the title screen). It also does not advance during the deck editing menu (CHEST, DECK, DUEL) that appears after the final pre-duel text box. So to RNG manipulate duels, you want to select a duelist frame perfectly (or within a small cluster of frames), then route a cluster of frames you might hit when clearing that text box.

Several inputs can be buffered. After hitting CONTINUE with the Start button (not A), you can buffer A to frame perfectly reach Tier 1. From there, the only two duelists you can buffer are Espa Roba (right, then A) and Tristan (right, then left, then A). The reason you can't buffer Tristan immediately, or buffer Simon or DarkNite at all, is that the game does not accept consecutive buffered inputs from the same button (e.g., A-->A). You can buffer the up/down inputs to reach duelists such as Joey, Kaiba and Ishizu, but not the A input to select them.

On the duelist maps, the RNG seems to advance cyclically through a finite number of states. During text box screens, it seems to advance linearly through an infinite number of states. Thus, the size of the cluster you must route is equal to the number of RNG states on the duelist maps multiplied by the frame window you want to allow yourself for clearing the final text box. Good players can consistently hit a 4-frame window, and it's fast to reset if you mess up.

(Let's say the duelist map is limited to 6 RNG states and you're OK with a 4-frame window. You would route 4 duels for Espa Roba and Tristan, and 24 different duels for everyone else. If you hit the first RNG state and the first text box frame, that's duel #1. If you hit the third RNG state and the third text box frame, that's duel #11. Etc.)

Unfortunately, each duelist has different dialogue the first time you face them, and it's often several seconds longer than the normal dialogue. So if you wanted to avoid making a separate manip for the first duel, you'd have to make sure all the manips waited several seconds before clearing the final text box.

When deciding your starting hand, the game just looks at the slots (1-40) that your cards occupy in the deck editing menu. So if you find a manip that starts with slots 10, 15, 22, 29 and 33, you want to edit your deck so that those slots have desirable cards. Since this run will likely require hundreds of manips, deck order optimization will be difficult.

Once you've executed a manip, the duel will always progress the same way. Your starting hand, the opponent's starting hand and your opponent's moves will be fixed, with no RNG variance. Obviously, manipping a great starting hand for yourself, and a poor one for your opponent, is optimal. But just as important is the ability to perfectly predict what your opponent will do. For example, if you know DarkNite will lead Jirai Gumo, you could set Darkfire Dragon and let him suicide into it. Even if your starting hand isn't great, you can get a fast duel by playing smart.

The fastest way to win a duel is with Exodia. Even if you have to wait a few turns to draw all 5 pieces, it's faster than winning normally. However, finding such a lucky duel would likely require an emulator bot, and these duels wouldn't exist in clusters, so execution would be difficult. You also need to win 35 duels before you have the deck capacity to add Exodia's head.

Drops are also fixed at the start of a duel, so they can be manipped easily. Good drops allow you to run multiple copies of OP cards (you can only password one copy), and they might save a few password inputs (13.5s each). With the cluster method, your drops won't be the same every run, so you want to avoid relying on them too much. You might want to use passwords as backup strats for failed drop manips.

The following drops would be especially useful:

DUELIST			DROPS
Joey			Dragon Zombie, Eatgaboon
Yugi			Catapult Turtle
Mako			Eatgaboon
Mai				Armored Zombie, Eatgaboon
Espa Roba		Stop Defense, Bear Trap, Anti Raigeki
Seeker			Invisible Wire, Anti Raigeki
Rex				Stop Defense, Bear Trap, Anti Raigeki
Weevil			Cocoon of Evolution, Bear Trap, Anti Raigeki
Pandora			Fire Kraken, Invisible Wire, Anti Raigeki
Kaiba			La Jinn, Crush Card, Invisible Wire, Anti Raigeki
P. Seto			La Jinn, The Bistro Butcher, Gemini Elf, Dark Elf, Crush Card, Acid Trap Hole
Simon			Acid Trap Hole, Dunames Dark Witch
Ishizu			7 Colored Fish, Giant Red Seasnake, Acid Trap Hole
Heishi			Mechanicalchacer, Acid Trap Hole