Unfortunately, the game failed completely. For what reasons it is difficult to say. It's too good for smartphones, too bad for PCs. The game has good ideas, a very good combat system, an interesting character leveling system, but unfortunately...

good game but server ping too high if had Offline Single Player version ...

Well, post-mortem assessment, I do think this game deserved a longer life, but I feel it had some major ping issues and grind/repetition.

It's ironic as someone who juuuust managed to complete all the content released before things went offline (including reaching the very end of the buggy first mission for the third chapter of conquest), it's kind of bitterly ironic I feel that the game really seemed to "pick up" at the end of the Main Mode. Prior to the final battle with Queen Consort Cho every mission fits into the same molds, especially the Three Act-plus-Boss Fight one where you try to fight your way through a parade of mooks and minibosses to the enemy alone, and Queen Cho's level does nothing to give an indication otherwise.

But when you actually HIT her final battle, ZOMG you are in a major, major battle involving not just the enemy boss and a horde of zombies, but also FRIENDLY NPCS. Yeong Shin, IIRC Mu Yeong, and a horde of Royal Guards like those we had fought but allied. It was remarkable. And when I finally beat her, then we see the Conquest Mode story, which I think was really remarkable but makes a lot of sense, with the Japanese learning what happened in their initial invasion (small as it was), finding out about the Resurrection Plant and zombies and how badly Korea has been ravaged by the zombie outbreak and the Cho Clan's intrigues, and reinvading with weaponized zombies. At which point you have a sort of conventional but abbreviated level of fighting through Busan to kill a strengthening Japanese General, then have to defend a castle first against waves of zombies and then against a sophisticated Japanese attack by elite heavies and rocket gunners, and then fight a one on one duel against a Japanese General.

Then you have to try and have an odd stealth mission to assassinate another Samurai General while optionally trying to destroy shrines (which I think reallllyy showed the limitations of the game's engine given how this was very clearly not a system made with stealth in mind, and involved some cheesing), before finally having to go through a zombie infested field destroying supplies and then fighting a zombie boss/miniboss to escape.

While the third chapter allowed you to try and fight through an admittedly ♥♥♥♥♥♥♥♥ obstacle course of very strong Japanese troops (including the magazine-fed hand gunners who can act either as artillery or as shotgunners, and who yet are still not quite as BS as the humble Musketeer) on the road to a castle (unfortunately due to how development stopped even getting that far means you can't progress there). After which there'd probably have been another battle to kill another Japanese General and then having to defend the held castle against another zombie horde. All against the backdrops of cutscenes.

I feel like the dev team were kind of "hitting their stride" in many ways. The levels were shorter (and in some cases more contrived), but also more unique and fresh. And the plot I feel (outside of the question of why Ashin would be helping Joseon again in the invasion beyond "We need to have her fit with the same content as Lee Chang") is out of left field but also very logical. People often forget there were two distinct waves of Japanese invasion in Korea in the 1590s, and the Japanese are obviously not incapable of learning about the Resurrection Plant and zombies, and still have a massed, battle hardened, and modern war machine ready to invade (in part due to how the first invasion was such an early failure on land, meaning ironically that the Pro-Hideyoshi land troops and naval assets are more intact due to not having to go through multiple years of fighting in Korea).

And frankly given the historical antics of Hideyoshi in Korea and his homeland, I don't think of a convincing reason why he wouldn't use zombies.

It was a fresh way of game design and gameplay, and an interesting and IMHO fitting continuation of the Kingdom story in much the way of "Well if it isn't the consequences of Lord Anh and the Cho's actions." that also mirrors history. It is kind of sad to realize how few people would have gotten to see any of it at all. It also makes me wonder if this might be something that's the result of talks with the Show Team on where they plan to take things.