When I first skim read information for this game, I thought it would be one that I'd probably have a hard time finding in order to play in the first place. It's a Neo Geo Pocket Color title, a handheld that I've never seen in my life. In my experiences, you either had a Game Boy Color to play Pokémon or you didn't. There was no Neo Geo round our way.
The Neo Geo Pocket Color itself had such a hard run competing against Nintendo devices that the number of games available for it wouldn't even fill a top 100 list, but, according to this 1001 list, there is a title that simply must be played, and it is SNK vs. Capcom: Card Fighters' Clash.
Take a bunch of SNK characters, a bunch of Capcom characters, make them into a Magic: The Gathering-style card game... oh we're going to be all up and down on this one, I can feel it.