Unfortunately, at this point in time Halo Wars 2 does not contain a split screen option. Youll need to stick with Xbox Live and online for now, in order to play campaign co-op and multiplayer modes.
Is Halo Wars split-screen?
Yes! You can play in co-op mode locally, as well as multiplayer gaming with 2-6 players on either Xbox One, Windows 10, or Steam: Xbox One players can play with other Xbox One players.
Can you split-screen Halo 2?
The multiplayer split screen type is determined by the video settings on the Xbox dashboard. From the main menu, choose Settings and then Video. For horizontal split screen, the Xbox must be in normal mode (see Figure 4-1). For vertical split screen, the Xbox must be in widescreen mode (see Figure 4-2).