Densha de Go! (Go by Train) (Cyberfront/Taito, 1999)
A long running Japanese train sim, now on GBC. Train sims are at least something pretty to look at on modern systems, but here it's just watching vaguely area-appropriate green scenery scroll past.
Densha de Go 2! (Cyberfront/Taito, 2000)
Basically the same game. It had the Shinagawa -> Ueno section of the Yamanote line playable, so since I've been on that train quite a few times I figured I could at least see how it compares to reality. It does an okay job of it considering it's on GBC, actually, and I appreciated the authentic doors closing jingle it played when I started the train. But it's still really boring.
Dexter's Laboratory: Robot Rampage (Infogrames/Bit Managers, 1999)
Never liked the TV show, and this crappy game isn't going to change my mind. It's one of those games with an elevator and a bunch of doors where you're trying to get to the other end of the screen and shoot some baddies along the way. Never liked that genre, either.
Dino Breeder 3: Gaia Fukkatsu (Gaia Revival) (J-Wing, 1999)
Another Tamagotchi-style animal raising game, except that there's combat. I was not expecting the professor to volunteer to fight my baby triceratops when I pressed the fight button, but that's what happened.
Dino Breeder 4 (J-Wing, 2000)
For once, not even remotely the same game. Now you're playing as the professor and time traveling to dinosaur times to character platform some dinosaurs. The platforming is really bad and touching an enemy instantly resets you to the start of the screen. Maybe they should've stuck with tamagotchi.
Dinosaur (Activision/Prolific, 2000)
Top down action game based on yet another forgotten Disney movie. It's not really remarkable for anything other than B being a dedicated horrible noise button. You can press it rapidly to make the noise even more horrible, and then presumably your parnets would throw your GBC into the ocean and you'd need to find a new hobby.
Dinosaur'us (Electronic Arts/RFX Entertainment, 2001)
Although you'd never guess it from the screenshot, this is a character platformer starring a dinosaur who changes color after touching certain leaves. What you're seeing is a random encounter, because why wouldn't you have random Pokemon battles in a platformer? Nothing I saw explained why there's a "'us" tacked on to the name.
Diva Starz: Mall Mania (Vivendi/Digital Eclipse, 2001)
I've always found the Diva dolls deeply uncomfortable, so I was thankful that the character you actually play as in game looks nothing even remotely like the Diva character you choose to play as. The first level was an autoscroller where you could jump to collect your "fab stuff" that had blown away, and it was very boring.
Dogz (Mindscape/Saffire, 1999)
If you remember Catz from a few posts ago, this is that with a dog. That's it. Nothing else changes.
Dokapon?! Millennium Quest (Asmik Ace, 2000)
Wikipedia describes this as an action game, which is weird because it's actually a traditional roguelike. There were a lot more of these than I ever realized on GBC, and although this one doesn't seem as interesting as others that have come up so far, it does at least give you your choice of player character. And it seemed like combat was decently deep.