Sgt. Rock: On the Frontline (Altron/BAM! Entertainment, 2000)
The music sounds like someone clicking randomly in Mario Paint, but the run-and-gun gameplay is kind of fun. I'd have considered it for the list except that the first area ended with a really cheap massive wave of guys, and that led to me learning that running out of lives makes you play the entire level again. No thanks.
Shadowgate Classic (Infinite Ventures/Nintendo, 1999)
It seems like a solid enough port of the famous adventure game. Unfortunately for this cart, said game has been ported to much newer systems, so there's basically no reason to touch this version.
Shaman King Chou Senjiryakketsu: Funbari Hen and Meramera Hen (Studio Saizensen/King Records, 2001)
A card game based on a manga in two versions. They don't seem to be very different from each other, at least not compared to how different they are from themselves if you just pick a different protagonist. Unfortunately, both the cards and kanji are a little too low-res for me to really consider playing this.
Shamus (Junglevision Software/Telegames, 2000)
This looks like a 2600 game, and whoever decided this was acceptable for release in 2000 should be banished to 1975. It does not play or sound any better than it looks.
Shanghai Pocket (Sunsoft, 1998)
It's that solitaire spinoff of Mahjong that was really popular with casual gamers in the mid-2000s where you need to match pieces on top until you clear the board. I went in with basement-level expectations for this, but it's actually kind of fun and the music is fantastic. I probably won't finish it, but it gets a list spot thanks to whoever the composer was. It also has two other modes that I didn't try today.
Shantae (WayForward/Capcom, 2002)
Even though it came out at the very end of the GBC's life, Shantae is still a very common answer to "best GBC game", and it put WayForward on the map. It's not hard to see why even from the few minutes I played today - pretty much everything except Shantae's crummy sprite are well ahead of its contemporary handheld platforming competition. There are ports to newer systems now, but the original has to get a list spot.
Shaun Palmer's Pro Snowboarder (ITL/Activision, 2001)
This was Activision trying to get a second Tony Hawk, and they were so subtle about it that they copied the box art. On GBC, at least, it's practically impossible to tell what's going on, and you wouldn't be able to do anything but react to the course unless you had it memorized. There are many better things to commit to memory than this game.
Shin Megami Tensei Devil Children: Aka no Shou, Kuro no Shou, and Shiro no Shou (Multimedia Intelligence Transfer/Atlus, 2000/2000/2001)
Despite following the Pokemon format of two simultaneously released versions followed shortly by a third, all three of these are completely different stories that just share gameplay mechanics. I didn't play enough to get to gameplay because Aka no Shou combines some of the best music I've heard on GBC with being one of like three times Atlus had a female lead, and that's enough to get me interested in a longer play. The other two may join the list as well depending on how Aka turns out.
Shin Megami Tensei Trading Card: Card Summoner (Enterbrain, 2001)
This came out in 2001, yet it looks like this and has terrible music. You can tell it's very good because Wikipedia doesn't even bother linking it back to the SMT series, and the SMT wiki's page on it basically just says it exists. Despite that high praise, it's actually not fun at all and I won't be coming back to it.
Shinseiki Evengelion: Mahjong Hokan Keikaku (Studio Saizensen/King Records, 2000)
I know nothing about Neon Genesis Evangelion, but if anything was ever going to convince me to find out what it is, it would be the series only representation on GBC being a mahjong game. Isn't this series about mech battles? Why are they suddenly in a school playing mahjong with an old man? Oh, and I still don't know how to play ricci mahjong. Just in case you were wondering if that had changed.
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
Metal Gear Solid
Millennium Winter Sports
Pokemon Crystal Version
Pokemon Card GB2 - GR Dan Sanjou!
Pokemon Puzzle Challenge
Pokemon Trading Card Game
Quest for Camelot
Return of the Ninja
Scooby Doo! Classic Creep Capers
SD Hiryuu no Ken EX
Shin Megami Tensei Devil Children: Aka no Shou