This game has been out on PS4 for about 9 months, coming to steam soon. I have clocked around 300 hours on PS4 on mostly just single player non-pvp content, and I intend on buying the PC version when it comes out. The best way I can describe it is a game with Dark Souls / Bloodborne-esque combat with punishingly difficult bosses (until you learn them) but with a Diablo-esque loot and equipment system that gives a (imo) great and lengthy endgame grind. That means you get items with set bonuses and lots of affixes/properties that you need to farm for and reroll to make them perfect: The setting is feudal Japan and you fight as many yokai (demons and ghosts) as you do ninjas and other samurai. You fight with melee weapons like katana (single or dual wield), spears, and axes but you also have access to ranged weapons (bows and matchlocks), ninjutsu (stars and kunai), and magic (elemental spells and buffs). The co-op system in this game is MUCH better than Dark Souls. You can join a lobby with a friend and do missions together (completing the mission for both players), or do a more souls-like summoning players who help you until you die or clear the mission. There is pvp which includes a mode that forces both players to use base level equipment for a balanced fight, but I haven't played it at all. There is no "invasion" style pvp. I can say the skill cap for combat in this game is extremely high, higher than Souls/Bloodborne because of the combat system which has multiple stances (somewhat like transforming weapons in Bloodborne) and other things I won't go into detail for. Finally, there's a 999 (nine hundred ninety nine) floor dungeon that serves as the somewhat lazy but ultimate endgame/postgame time sink. I cleared it on PS4 but definitely won't go through that again on PC. You can also become a parry god and parry any human-type enemy (including bosses) in the game. tl;dr The world's first weeaboo travels to Japan to rescue his ghost waifu and study the blade. He manages to change the entire history of Japan without ever bothering to speak or learn Japanese. Somehow everyone else just understands when he speaks in English. There is unresolved sexual tension between both the weeaboo and a female ninja and the weeaboo and a male ninja. source http://store.steampowered.com/app/485510
I remember reading about this game prior to it's release. I intended to buy the game, but ended up not doing so. It looks interesting though!
I played Nioh at a friend's house a few times and I think one of my mules is named NIOH (yes now I'm oozing with credibility). The game is quite entertaining and extremely challenging. It's basically Dark Souls, with some differences that you noted. It was hard for me to get into it because of how slow early game combat felt, but I watched my friend play his character with all sorts of jacked up stats and it looked amazing. I might be a little interested in the PC release.
It's out now and I'm going to be streaming the PC version until I get bored. It came out at midnight for me yesterday so I only played the prologue and first mission (prologue not streamed).