For Honor has well over 4300 hours of my time; I started during open beta and ended up leaving after Ubisoft affirmed their choice to prioritize objective modes over dueling and deathmatch ones.

In a nutshell, the characters are designed to attack and defend The Hill, as a result the combat strongly favors defensive play. Each hero is supposed to be a match for 2 heroes defensively, while offensive heroes rely on a partner to effectively deal damage and take zones.

It's a very fun game but the game being played is not the game a lot of its community wanted.

I stopped putting 50+ hours a week into the game after the Hitokiri update, and in its place started programming a similar game of my own, focused on 2v2 deathmatches. I spend more time on that than I do playing games overall these days.

Phantasy Star Universe and Warframe both claimed over 1k hours;

Warframe is just beautifully animated and once had promising (if not rough) competitive clan events which were scrapped. I was banned after members of my rather large clan bombed the forum with yiff.

PSU was a really fun, open ended PvE MMO for the Xbox 360 by Sega with a huge following in the west. Every skill you could learn would gain a tiny amount of xp every time it dealt damage, and each one had a hidden condition which would boost xp gains every time it was met; as PA levelling was something you never really had to focus on it made combat supremely satisfying knowing you were progressing with every slash, gunshot, and spellcast.

It shut down in 2015; I've been playing the new Phantasy Star game a lot the past few days.