CDKeys offers downloads of Halo Wars 2: Ultimate Edition for Xbox One and Windows for $52.89. That's $3 under last week's mention and the lowest price we've seen. (It's the best deal today by $17.) It includes a Halo Wars 2 Season Pass download.
Note: New customers can provide an email address on the CDKeys Facebook page to get a unique coupon code that cuts an extra 5% off.