The Killer Instinct team is doing something interesting. Since launching on Xbox One, the game has moved on to both Windows 10 and Steam. Now the latest Content Update, version 3.9, is bringing everyone together. But as it goes live, the developers will be actively tinkering to make sure it’s as smooth an experience as possible.
The latest Content Update for Killer Instinct actually adds a toggle option to turn Cross-Play with Steam users on or off. This is purely for connecting to the Steam side, as Xbox One and Windows 10 are natively connected already.
The Killer Instinct update stresses that this toggle option can at times either turn itself off or disappear entirely. While this option is live for everyone, it is considered a live stress test, and the developers will be actively supporting, tweaking, and changing how it works as deemed necessary.
This is yet another big example of Microsoft actively seeking out avenues for cross-play across userbases. It's something the company seems to be actively fueling as a hot issue while the competition is in talks to participate.
Source: Killer Instinct Official Forums