Shin Megami Tensei Devil Children: Aka no Shou
I put this one on the list almost entirely because it's an SMT game, but I ended up hardly playing any of it. That's partly due to the music, which is grating, and mostly due to the font, which is awful to read. I might have stuck with it despite those issues if there was more to it, but even contemporary reviews were just middling and the lame graphics in that screenshot should give you a sense of how low budget the whole thing is. It's vaguely interesting as one of the only SMT games that doesn't cast you as a high school boy, but that's about all it has going for it.
This is the sort of hidden gem that I did this whole project to find. It's a puzzle-platformer where you have three weapons: your hyouta, which turns enemies into blocks, your katana, which kills enemies, and your ouen, which hypnotizes enemies into following you. Gameplay consists of using those abilities (and a wide assortment of mechanics added later) to get blocks where you need them to reach the next room. Each stage ends with a boss fight that mostly ditches the puzzles for good-old 2D action, which is a nice change of pace.
The best news for most people reading this is that, even though it was a Japan-exclusive game, the language barrier is minimal. SK is amazing at "show don't tell" design and even though there are a few Japanese hints per stage, most of the puzzles communicate their mechanics well enough without text.
This probably won't be quite my favorite GBC game over all, but there's a good chance that it'll be the one I recommend most strongly today: Samurai Kid is still a great game now and there's very little else like it.
Pokemon Card GB2 - GR Dan Sanjou!
The sequel to PTCG is basically the same game with more story. That approach to sequels is fine for a lot of games, but PTCG had some fundamental gameplay issues around RNG and energy cards that desperately needed to be addressed. To the extent that it addresses those problems at all, this game makes them worse by forcing you to use a fire deck that burns energy with all of its good abilities. The story is Pokemon, so you probably won't be shocked to know it's not anywhere near good enough to make up for the frustrations of the gameplay.
Honestly, the whole thing feels like a quick cash-in. It reuses all of the first game's music and even has exactly the same map, so it can't have taken much effort to transform the first game into it. I imagine that also explains the lack of an English translation.
This is a GameBoy Color game with full voice acting, which is extremely impressive. Unfortunately, that seems to have been the only thing they could fit on the cart, because there's almost no music or variation on environments, and gameplay consists of shooting clones of the same guy over and over again. Navigating levels is a nightmare because everything looks the same and there's almost nothing to find except more of the clone army.
I think I'd still recommend trying a few minutes of it just because it's so cool that it exists on GBC, but it's not at all fun to play.
This was one of the games I was most looking forward to on the list because there were decisions made in its translation. You're asked to pick between playing as Kenta, who "is strong and can go to school", or Sumire, who is "better than boys" at the start of the game. There's clearly supposed to be some level of comedy in a game about raising a monkey to take place in boxing matches so that you can rescue your monkey-training father from a gang of evil monkey trainers who are trying to mind control him to work for them. But even so, the localization really carries the humor to another level.
Unfortunately, the game itself is a very boring Tamagotchi-style thing where you make a couple of decisions per day and mostly just watch your monkey walk back and forth without doing anything interesting. It's a real shame that the regular gameplay is so bad when the story got so many laughs out of me, but I could only stand to play about a half hour.
Current status of the list: (Good games are bolded, green means finished and orange means abandoned. Bold means a game I'd recommend today)
1. Alone in the Dark: The New Nightmare
2. Arle no Bouken: Mahou no Jewel
3. Bionic Commando: Elite Forces
4. Cannon Fodder