Looks like Halo will return on PC pretty soon… even if not in its FPS incarnation. Halo Wars 2 has been just announed on the stage of Gamescom 2015 by Microsoft and it will be exclusive for Xbox One and Windows 10.
The first Halo Wars came out on 2009 and was developed by Ensemble Studios. The sequel is developed by Creative Assembly, developers of the Total War franchise.
Halo Wars 2 has been announced to come out at Fall 2016