Wings of Fury (Magnin and Associates/Red Orb Entertainment, 1999)
A side scrolling flight game set in WWII. This was originally an Apple II game in 1987 and was well received back then. I'm not sure why, though, because endlessly flying left and missing all the targets because they pop up with no warning at all isn't much fun. I gave up after I got past the first island and had nothing but water to look at for a solid 30 seconds.
Winnie the Pooh: Adventures in the 100 Acre Wood (Tose/NewKidCo, 2000)
A roll and move game starring Winnie the Pooh. It seems like there are 8 stages and that you can eventually unlock minigames outside of the board game, but I don't want to play enough to find out.
Wizardry: Proving Grounds of the Mad Overlord, Wizardry II: Llygamyn no Isan, and Wizardry III: Diamond no Kishi (Game Studio/ASCII Entertainment, 2001)
All three of these are ports of early 1980s RPGs that were hugely influential for their time, but also wholly unremarkable by 2001. They all have identical setup menus and are only really differentiated by the color scheme of each dungeon. The GBC ports, which were all Japan exclusive, released on the same day and should've been on one cart. Even combined they'd be far from the largest game on the system.
Wizardry Empire and Wizardry Empire: Fukkatsu no Tsue (Starfish, 1999/2000)
More Wizardry, but this time with a town you can visit to do all those menu functions. It also has a coliseum for fights and a few other things that weren't in the older games. Dungeon crawling, however, is indistinguishable from those. These two games were original releases, not ports, and never made it out of Japan.
Woody Woodpecker (Planet Interactive/DreamCatcher Interactive, 2001)
A platformer in which you climb Woody Woodpecker's impossibly tall house and collect items for no reason, all while being attacked by other items for equally unclear reasons. You have an attack, but no one seems particularly bothered by it, and the music is on a loop that takes all of about three seconds to repeat.
Woody Woodpecker Racing (Konami, 2000)
This actually has everything it needs to be a solid racing game, except that they capped your speed at about a quarter of what it could be. It feels like you're playing the game in slow motion, and that's never something you want to be saying about a racing game. Also, this is supposedly the "city" track, but it clearly takes place in the woods.
Worms Armageddon (Infogrames, 2000)