"When your master speaks, I expect you to bark!"
Oh, right. The Dungeon Dice Monsters interlude. Alright, let's do this.
Of all of the filler arcs, this is by far my personal least favourite, and probably Little Kuriboh's too since in Yu-Gi-Oh! abridged, the big joke is that Dungeon Dice Monsters (DDM) as a game is just Duel Monsters with dice.
I actually don't think that's the case, because in the manga at least, DDM establishes the rules and gameplay well enough to cement it as a different type of game that relies on different enough mechanics from Duel Monsters to have a distinct identity. What it is, however, is a pretty shameless reboot of Capsule Monsters (that's right: nothing gets past me!), but more easily translatable to real world gameplay.
Just like Capsule Monsters, DDM probably wouldn't work as an IRL tabletop game because, tragically, we haven't yet had a Seto Kaiba to invent Solid Vision, but it does/would work as a video game in a way that Duel Monsters doesn't really lend itself to -- for whatever that's worth.
Whatever, none of this really matters because even Takahashi seemed to view this episode as pointless since everything about it draws on more interesting storylines we've already had. Joey/Jonouchi loses a game to someone obviously savvier than he is in an embarrassing way and gets called a dog by someone cooler and hotter than he is who is a teenage game developer that runs his father's business... hmmm
(Side note: just to address the elephant in the room, if we had a quarter for every game developer and business owner in Domino that has had a quasi puppy-play relationship with Joey/Jonouchi we'd have 2 quarters. Which isn't a lot, but it is weird that it happened twice).
Then, Yugi steps in and is all 'don't talk to my friend like that!' and our absolutely not derivative and very distinct and three-dimensional villain of the week, Duke/Otogi slowly reveals that he was actually after Yugi all along.
In another 'sins of the father' twist, it turns out that Duke/Otogi's father was a mentee of Yugi's grandfather in the past, lost to him in a Shadow game, and was horribly disfigured as a result. Ever since, he's had it out for Yugi's grandfather, and passed that grudge along to his son, who now resents Yugi by association.
A few things happen in between, but the key point is that Duke/Otogi lures Yugi away from his friends, takes the Millennium Puzzle off of him, and forces him to play DDM to get it back.
In this version of events, Duke/Otogi's plotline is crossed with the Millennium items, and he believes if he can defeat Yugi at DDM, the power of the Millennium puzzle will transfer to him.
On the one hand, this is kind of interesting, and even Yami Bakura is given something to do because he shows up as Yugi's cheerleader (???) and proclaims that only Yugi can wield the Millennium Puzzle; anyone else who tries will pay a heavy price. Except maybe Kaiba in Darkside of Dimensions for some reason. Whatever. Don't worry about it.
Personally, I prefer the anime version of this plot because, frankly, the set up in the manga doesn't really add to either the lore or the worldbuilding. At least in the anime, Duke/Otogi's motivation is more integrated into the overarching narrative, and is grounded in already established events. In the anime, his issue with Yugi is that prior to the Duelist Kingdom tournament, Duke/Otogi had been promised by Pegasus that after the tournament was over, they could discuss Industrial Illusions backing the development of DDM because (Pegasus assumed) after Duelist Kingdom, Industrial Illusions and Kaiba Corporation were set to merge, which would give Pegasus access to the Solid Vision technology necessary to make DDM market viable.
But, of course, that doesn't happen because by the time Duelist Kingdom is over... Pegasus is dead. Or missing. Or otherwise out of commission. Little sketchy on the details.
And Duke/Otogi blames Yugi for this, which is why he wants to in some manner or other make Yugi pay.
Doesn't that sound a little better? A little more complex? Still a bit dumb, but at least less...contrived?
The only good thing to come out of all of this in the manga is that Yugi gets a little bit of character development, since he has to defeat Duke/Otogi on his own. And we start to get a better sense of Yugi as a personality distinct from Yami Yugi, and we also get more evidence to suggest that even without the help of ancient Egyptian magic, Yugi is a savvy gamer in his own right.
But, surely, we could have gotten this development in a more satisfying way.
Oh! And we learn/are reminded that in the manga-verse Yugi actually lives with his mom, and she has like, two lines of dialogue. So, that's nice.
Ah, well, at least it only takes a volume and a half to get us through this on the way to the start of Battle City!
Random piece of lore: we learn on page 11 that while his soul was floating around (???) Yugi’s grandpa meets up with his grandmother (‘s soul???) before retuning to his body in Domino (???)