At the brink of its first bankruptcy, SNK did this excellent polished version of KoF 99 which added more strikers and 3D backgrounds, a PC version came out after the initial Dreamcast release, but it was quite difficult to find due to a limited Japanese release. I first heard of this in fan forums, who just like me, wanted to check this out, it was nearly mythical, since many of us didn't get a DC back then, we were limited to PC.
Regardless this would be amazing for GOG's preservation program, it's a really good fighting game, with good visuals, great music that got overshadowed due to SNK going bankrupt and the generational change which only saw this version being released on the Dreamcast as far the consoles of the time were concerned. I would always play a session whenever I'd see this in an arcade (With a modified dreamcast acting as an Arcade machine), it got all the good of the original KoF 99 and made it better and KoF 99 being the beginning of a new story arc and daring to try different things with the formula with the strikers and teams with 4 members instead of the traditional 3 was a bold strategy.
Hope to eventually see it here.