First off, sorry if this is the wrong place, or if there's some other error with my post, I'm sure the mods will correct whatever issue comes up lol

I've been trying to develop my own strats for this game, so I've been testing this game off and on for a while. So I wanted to ask a few questions about the RNG, to anyone that knows much about it:

1. Is there a particular method for how card drops work?

• I feel like if there was some way to manipulate it, someone would have found it by now, but figured I'd just ask. The spreadsheet (big help by Froggy25) lists them by individual duelists, so we know it's from a preset list, but how does it determine exactly which drop it will give?
• And to just tie to this question, I've gotten Blue-Eyes White Dragon as a drop entirely randomly, from people outside whom you'd expect (Kaiba & P. Seto). Could we assume there's a small chance you could get it from anyone, and does any other card work like it?

2. How exactly does the AI prioritize the cards it will play for a turn?

• The AI is fairly predictable, in that for monsters it will play the highest card cost it can. So for 2 cards with equal cost, would it just play the one with the highest ATK?
• Mainly for the early game, if the AI has a chance to destroy something via attribute, will it always go for it? For example, if Yugi has Flame Viper, and you have Jirai Gumo, would he always attack it 100% of the time? What if you had a weaker monster, something like Leghul instead?
• It's clear that the AI likes to wait to use some of the stronger cards in game, such as Dark Hole, Raigeki, Crush Card, Swords, and a few others. I think for Yugi particularly, if he opens Dark Hole, he sometimes likes to wait until you have 3 monsters on the field to use it. I think for everyone else, they will use those cards when they cannot destroy your monsters by battle, run into your trap cards, or can't summon for the turn. And of course, there's always topdecking an out, but I'm sure there's a little more to it.

There's a bunch more I could say, but these were the issues I've thought about the most, and would have no idea how to really find out myself without testing for hours and hours lol. If possible, this can be turned into a general info dump on RNG and AI; I don't think there's many other good resources for this game outside of this site and maybe a couple GameFAQ's faqs. Thanks for any info you guys can offer :)

Hello, I just noticed your thread... You might have a look at this if you want to explore the guts of this game: http://datacrystal.romhacking.net/wiki/Yu-Gi-Oh!_Dark_Duel_Stories:ROM_map This is still a Work In Progress, which will be moved on GitHub in the future. I'll finish this answer later, too many details for a clear answer. Will try to do a tree for the AI priority.

1. Which emulator were you using ? The BEWD drop is a common issue when using inaccurate emulators, such as VBA or KiGB (issue with Memory Write timing which causes the card drop writing to fail, so you get the default 0x00 drop, which is BEWD). A number between 0 and 2047 is generated, and it sums the odds of each card until it is greater to the value generated. Then it drops the card on which it stopped adding numbers. http://datacrystal.romhacking.net/wiki/Yu-Gi-Oh!_Dark_Duel_Stories:ROM_map#Determines_which_card_to_give_after_a_duel

2. I hope I forget nothing too important: (on hold) a. CPU checks if you have a Trap in play a. a. If you have a Trap, CPU checks if it has 2 or more Change of Heart in hand a. a. a. If CPU has 2 or more Change of Heart in hand, it summons a monster in Defense position a. a. a. CPU ends its turn a. a. b. CPU checks if you have at least one monster in play. a. a. b. a. If you have at least one monster in play, CPU checks if it has Harpie's Feather Duster in hand a. a. b. a. a. If CPU has Harpie's Feather Duster in hand, CPU plays Harpie's Feather Duster a. a. b. a. CPU tries to do as many Fusions as possible a. a. b. a. CPU checks if it can Tribute summon a. a. b. a. b. CPU Tribute summon highest cost Monster a. a. b. a. CPU checks if it can summon a. a. b. a. c. CPU summon highest cost Monster a. a. b. a. CPU tries to play as many Equip as possible (stopping at +2) a. a. b. a. CPU checks if it has monsters that have ATK less than half their DEF value (i.e. 500/1300) a. a. b. a. d. CPU put these monsters in DEF position a. a. b. a. CPU checks if it has at least one Monster that can attack a. a. b. a. e. CPU checks if player has a face-down Monster a. a. b. a. e. CPU attacks that card with highest ATK monster a. a. b. a. e. Loop until no more face down monster on Player's side, or no more Monster can attack a. a. b. a. CPU checks if there are face-up ATK position monsters on Player's field a. a. b. a. f. starting by highest ATK monster on Player's field, CPU checks if one of his monsters has Attribute advantage, starting with its lowest non-frozen monsters a. a. b. a. f. CPU attacks with Attribute advantage a. a. b. a. g. CPU checks if there are face-up DEF position monsters on Player's field a. a. b. a. g. starting by highest DEF monster on Player's field, CPU checks if one of his monsters has Attribute advantage, starting with its lowest non-frozen monsters a. a. b. a. g. CPU attacks with Attribute advantage a. a. b. a. h. starting by highest ATK monster on Player's field, CPU checks ATK values of ATK position Monsters on Player's field, and checks if one of his monster without Attribute disadvantage has an higher ATK value a. a. b. a. h. CPU attacks with higher ATK

(Will finish later, will make a tree for this)

Froggy with the hard work 0_0 thanks for the effort man! I know nothing of hacking games and roms myself, so I'm a dunce when it comes to that sort of thing lmao.

Yea the Blue-Eyes thing has only happened when I've used VBA emulators for testing, never with Gambatte.

The AI tree is extremely interesting; the way the AI summons and attacks in a certain order can get really particular.

I feel like I nearly understand how the AI goes about playing certain spells on its turn. Basically, you'll see it play all its spells either before, or after attacking. But it doesn't seem all that straightforward; of course, there are particular cards like Swords and Raigeki. But I wouldn't even say I've seen the AI play cards like Mooyan Curry, Red Medicine, etc. in a really consistent way.

But yea thanks again man, take all the time you need.

EDIT: Small question on the tree; in general I would say the AI prioritizes attacking sets before attacking by Attribute. But especially early game, I feel like the AI will try to destroy monsters with larger costs by attribute before attacking your set monsters. For example, say you fused for B. Dragon Jungle King, and then have a set monster on field. If you're dueling Joey, he may summon a Flame Viper, and attack B. Dragon instead of the random set. Just something I've seen over and over lol

Hey guys! I was curious. Can you edit the cards' odds? Is there an editor, for example, where i could modify some values? Thanks!