Well, Will, I'm sure we could discuss box art itself, though I was referring more to the titles themselves.
The box arts for the Mega Man games use the numbers 2-7, whereas the in-game titles say II-VII. (8 and 9 are consistent. Perhaps calling it "Mega Man IX" will add to the confusion that already exists since so many people still think Mega Man X means the number 10 when it really means the name X...) You may have noticed that I typically prefer the in-game title, especially since I use in-game shots on the Atlas pages, so I call this game "Mega Man II".
I'm not really sure where the idea to use numbers for the NES games and Roman numerals for the Game Boy games came from. Because the NES games clearly use Roman numerals in-game, you'd probably have to specifically mention "Game Boy" whenever you're talking about the Game Boy games anyway.
"Ninja Gaiden (Episode) II: The Dark Sword Of Chaos" has the apparently optional word "Episode". I probably don't usually say "Episode" every time I refer to it, but I would think it would be weird to have a link to its maps here on VGMaps.com without it reading "Episode" since it's clearly there in the image.
As for "Snoopy('s Silly Sports Spectacular!)", it seems to suffer the same fate as "Mickey Mouse(capade)". In Snoopy's case, since it's not about his usual adventures of lying on top of his doghouse, hanging out with Woodstock, pretending to be Joe Cool or trying to shoot down the Red Baron or anything like that which he does in the Peanuts comics, it really sounds like the box art has an accurate description of this particular game. I also don't like using just the character's name to refer to a game if the character hasn't originated in video games. It's fine to say "Hey, have you played Super Mario/Mega Man/etc.?" but it sounds weird to me to say "Hey, have you played Snoopy?"