Xbox head honcho Phil Spencer appeared at the PC Gaming Show E3 press conference, something that has been long overdue in my opinion. He wore a buttondown dress shirt, so no gaming shirt that might hint to a future game. That said, the game he did mention should make fighting fans happy.
Phil Spencer, after saying that Microsoft lost their way for a while with PC games, announced that Killer Instinct is coming to PC. Players on PC can play with those on Xbox One, and vice versa. There's not a ton he said about it — it was a very brief announcement. But the fact that it's coming to PC and that's it's crossplay between PC and Xbox One is enough to be excited about.
We can look forward to when Killer Instinct will release on PC in the future.