Halo Wars 2 allows cross-play between 2 platforms

Supported crossplay platforms
Release Date: Feb 21, 2017
Official Website: Link
Summary:
After decades adrift and declared “lost with all hands,” the brave crew of the UNSC Spirit of Fire are mysteriously awoken above an ancient Forerunner haven known as the Ark. In Halo Wars 2, Captain Cutter and his crew will face one of humanity’s most formidable threats yet: The Banished – a fierce and powerful Brute faction led by a cunning and lethal warrior known as Atriox. Halo Wars 2 delivers real-time strategy at the speed of Halo combat. Get ready to lead armies of Spartans and other Halo fighting forces like Warthogs, Scorpions and exciting new units in a brutal war against a terrifying new enemy on the biggest Halo battlefield yet.
Supported crossplay platforms:
Halo Wars 2 is supporting cross-play across multiple platforms. Currently it is possible to play together with your friends on Windows PC and XBox One.
Supported game modes:
  • Multiplayer
  • Co-operative
  • Split screen
Supported player perspectives:
  • Bird view