Halo Wars: Definitive Edition has enhanced graphics, new achievements and includes all the DLC from the first game. But it is only available as part of the Halo Wars 2 Ultimate Edition bundle - at least for now.
Halo Wars Definitive Edition Minimum Requirements
Intel Core i3 or Equivalent
64-bit Windows 10
AMD Radeon R5 M240 / NVIDIA GeForce GT 740M / Intel HD Graphics 4200 with 512 MB