Mahjong Joou (Warashi, 2000)
"Mahjong Queen" is another entry in the bizarrely expansive genre of "GBC mahjong games where all the characters are women", but this time it at least includes you and quite a few of them look like they're in their 50s, so I think it's meant to be representative of the women's pro scene rather than "sexy mahjong" like the last one.
Mahjong Quest (J-Wing, 1998)
It has amazing music that, unfortunately, no one has uploaded anywhere. There's also basically nothing about this game online. Taito made an arcade game in 1990 by the same name that seems to be different, and a Western casual dev made a puzzle game based on Chinese mahjong shortly after this came out. It seems to be a ricci mahjong game with some vague RPG elements, but I'd have to learn how to play for real to find out.
Majokko Mari-chan no Kisekae Monogatari (Pack-in-Video, 1999)
It's based on a spin-off magical girl parody anime about a magical girl who has to go to human high school because she failed magical school high school, and now she has to avoid revealing her identity. The game seems to be a slice-of-life stat raiser with a really in depth clothing system despite the fact that your clothes don't change your overworld sprite. Seems decent, but the concept doesn't really do it for me.
Marble Madness (Digital Eclipse/Midway, 1999)
Everyone's favorite marble-based arcade game, now on GBC. Dpads aren't really the ideal way to play this game.
Marie no Atelier GB (TOSE/Imagineer, 2000)
I covered Elie no Atelier GB a while back, and you would be forgiven for thinking this is the same game given that it opens in practically the same room with nearly the same plot. They do differentiate themselves later on, from what I can tell, but Elie is the sequel and seems to have the more interesting systems. Not much reason to go back to the first Atelier game, then.
Mario Golf (Camelot Software Planning/Nintendo, 1999)
My initial reaction is that it doesn't seem like anything special compared to some of the other golf games I've seen on GBC so far, but I will be coming back to it to confirm whether that's true. Unfortunately, I'm a bit tight on time today and didn't get to see more than the first hole.
Mario Tennis (Camelot Software Planning/Nintendo, 2001)
It seems to limit you to playing as the slightly odd selection of Baby Mario, Luigi, and DK from the start. I will be coming back to see where it goes, but I was impressed by the graphics and music in the part of a match I had time for.
Marvin Strikes Back (Infogrames, 2000)
Crappy Marvin Martian game where you have really limited ammo and the game effectively softlocks when you run out because you're walking around a narrow path with no way to remove hazards except shooting them. Best forgotten.
Mary-Kate & Ashley: Get a Clue! (Crawfish Interactive/Club Acclaim, 2000)
I'm sure no one needs me to say that this is bad, but it's bad. It's really just a simple puzzle platformer despite pitching itself as some kind of detective game, and whichever one of the twins is in blue just stands there and doesn't contribute. Same for the dog. The only interesting thing about it is that they paid for quite a lot of incredibly compressed voice acting for different menu items.
Mary-Kate & Ashley: Crush Course (Crawfish Interactive/Club Acclaim, 2001)
In case you thought bad roll-and-move GBC games where an exclusively Japanese phenomenon, this game is here to prove they were global. It also wins the dumbest premise of all of these by tasking with with picking up more boys than the other players. That's a healthy attitude to have in high school!
Golf Ou: The King of Golf
John Romero's Daikatana
Kakurenbou Battle Monster Tactics
Keitai Denju Telefang
The Legend of Zelda: Link's Awakening DX
The Legend of Zelda: Oracle of Ages
The Legend of Zelda: Oracle of Seasons
LEGO Island 2: The Brickster's Revenge