Koei Tecmo is a Japanese game studio most known by the Dynasty and Samurai Warriors games - if people actually knew them, that is. Even though they put a lot of effort into most aspects of their games, there are very few people who even know about them outside Japan and China. It's a bit like my YouTube channel (I swear it's not a promotion attempt) - the content itself is decent, but not enough people know about it, so not enough people care. You can't say they really have active communities here, and even when people like them, they just play them as they are and barely try to have ideas for any fan content (unless it's about shipping characters of the same gender).
It's not fair that their games' quality is somehow not enough to make them stand out. I guess some of them have themes that don't appeal to the international market, like Asian history and mythology, but they deserve more attention from the west. The Toukiden series was the only one I really stuck with, but if the other Koei Tecmo franchises are made just as well as this one, someone should like them too. I'm not saying all of them have to be the next internet sensation like Friday Night Funkin' 2 years ago, but they shouldn't be the complete opposite either. Let me know in the comments if you know what makes these games so underrated and unknown.