Halo Wars: Definitive Edition will invade Steam on April 20, just two days away. The game was bundled with Halo Wars 2 on Xbox One and Windows 10, making the impending Steam release the original game's debut on PC. A Steam page for the game is already available.
This news carries historical weight. Ensemble Studios, which made a name for itself in the RTS space with the release of Age of Empires, closed up shop following the release of Halo Wars in 2008. Putting the game on Steam, where the largest percentage of PC players will be able to find it, all but guarantees that the game will be available in perpetuity.
The Steam release of Halo Wars: Definitive Edition will not support cross-play with the Xbox One or Windows 10 Store versions. That's not such a big loss; the Steam user base has the potential to be exponentially larger than the other two combined, so you shouldn't hurt for opponents if you decide to wait until April 20 to hop into a warthog and click your way around Halo's world, like God intended.