I've been in a GB yugioh games mood lately and, having never played this game before, I was surprised with how much fun I had playing this.

I suppose I should call this a spin-off, although this early into the franchise there was still some experimentation.

Monster Capsule GB is a weird mix of various elements from the manga:
-It uses monster capsules, but it doesn't follow it's mechanics from the manga (the Mokuba duels). It's more of an adaptation, taking some concepts and doing something different. It's also kind of a follow up to the ps1 game (at least the battle part), with simplified terrain and limited movement.
-Storywise, it's an alternate follow up to the Death-T, where after Kaiba got exodia'd he mysteriously came back to challenge Yugi to a Monster Capsule tournament. Characters from Duelist Kingdom appear and there's no explanation on how they know Yugi. The capsule roster includes monsters from the card game in addition to the original capsule monsters.
-The game also takes inspiration from the Monster World arc (that's where the cover art comes from). In each floor, instead of a boss fight you participate in a DnD session against a DM (dark master). There are 5 of these "campaigns" and their objectives vary from helping a dragon evolve, to preventing your monster being sacrificed to the great moth, to escaping hell. Gameplaywise these sections translate to more traditional rpg exploration, with fetch quests, puzzle solving and random encounters.

The result of all of this amalgamation of ideas is a monster collecting rpg with tactical rpg battle mechanics and table-top rpg-inspired exploration sections.
The combination works well, and in my opinion this is the best game at capturing the original feel of the manga. The monster world sections are the best part of the game, even though the last one is really long and frustrating, with a crazy strong final boss (the blue eyes fusion).

I can't give this game more than 4stars though, even if I really enjoyed it.
-It's grindy, and you get minimal exp most of the time. Evolution exists, but it resets the lvl back to lvl1. Sure you get more base stats, but most of the time it's not worth it since every level takes the same amount of exp (100 per level). The exp you get is calculated with the highest leveled monster you use in battle, so lower lvl monsters are deadweight. This also means that changing the monsters that you use will result in more grinding, but you cannot use your best monster to help since that will mean you get less exp...
-It's slow, setting the text to fast helps when you are in battles but it doesn't work outside of them. You can't run in the Monster World sections, and if you have bad luck the random encounters will be constant.
-Every monster can only move 1 space each turn, and even though you can bring 4 to battle, only 1 can move/act every turn.
-It has permadeath, and through most of the game you and your opponents die in 2-3 hits if there's no level advantage.
-Most of the time your hit rate will be about 70-80%. You (and most importantly your enemy) can crit if you roll from 1 to 9, super crit if you get a 00, and hit yourself if you get 95-99. All of this means you can get absolutely fucked by the rng, so prepare to savescum if you don't want to lose your best units to a random encounter (this is at it's worst in the final levels of hell).

This game is filled with "old school" rpg stuff and can get really frustrating at times. The start of the game is painful as you don't have many options and you level up so slowly. Once you get past the slow start it's not that bad... until the final sections of the game. Literally hell. Kaiba's world is the size of 3 "campaigns" with enemies that get worse and worse as you try to escape hell. The "final 4" ends in a crazy difficulty spike, with the blue eyes being way stronger than anything else in the game at that point.

My final story team was:
Winged Dragon (Guardian of the Fortress), the carry for most of the game, he only fell off at the end.
Dark Magician, he carried me in hell and killed ultimate blue eyes in a 1 on 1.
Great moth, literally deadweight, at the end of the game I had only reached the 3rd stage (of 5).
And Joey.

Overall, if you like yugioh and can stomach classic rpgs, or if you like monster collecting games, I recommend Monster Capsule GB. It's not as clunky as NES rpgs and I like how the story progresses. The DnD sections are great and the dice being visible every roll is a nice touch.

Since I'm crazy, not only did I beat the main story, I won against every opponent in the post game, built an extremely op team and I even got the Yugi capsule (though I wasn't crazy enough to grind him to lvl 50, the max level, so he could evolve into Dark Yugi).
I also completed the game on retroachievements. It was fun and made me go towards some secret stuff I wouldn't have done normally.

Game Review - originally written by (wraith)

This is a collection-based game. You know, the genre that revitalized Gameboy. I’d use the P-word, but calling this game a Pokémon clone tends to get Megaman X’s panties in a bunch.

Anyway, unlike Pokémon, you acquire monsters in this game by buying them out of a vending machine, or winning them (I think). I didn’t get very far, though, because the battle engine is too slow for my liking. It’s one of those dealies where when you fight, it switches over to a rather uninpired-looking grid, where you try to outmaneuvre your opponent’s monsters and beat them into oblivion. It’s almost as slow-paced as Gameboy Wars.

Can’t tell you much about the plot or such things due to the excessive amount of the game which is still in Japanese, but it involves rescuing your friend’s souls from some guy named Kaiba who awaiting at the top of an evil tower. Yeah.