Ubisoft's For Honor has had a rough time on Steam in its first week of launch. While having been one of the company's most popular beta titles, and with a large Steam population at launch, numbers after its first week in operation were reduced by half of its Day One player total of 46,000. After its second week, those numbers are even lower with 15,000 playing on a daily basis.
According to Githyp.com, much of the loss can be attributed to widespread server issues:
One of the main factors attributing to the game’s downfall has been Ubisoft’s own servers. Many players reported connection issues at launch that caused long matchmaking queues or even kept them from playing at all. To make matters worse, during its second post-launch weekend, a global server outage prevented the majority of the game’s owners from playing online.
The site further opines that these are the same drastic drops in population that affected The Division.
Of course, it must be said that For Honor is not a PC / Steam only release, but is also out on XBox One and PlayStation 4 and that even at 15,000 players per day, it is a "sustainable" population.