Command and Conquer and Red Alert both have DOS versions as well as Windows. The DOS one has very low resolution, but it means Dosbox is a possibility. But all

Command and Conquer and Red Alert both have DOS versions as well as Windows. The DOS one has very low resolution, but it means Dosbox is a possibility. But all in all, I'd say go with OpenRA. My friend and I played it for a couple of weeks and we scratched the itch of the original games, with none of the hardships and a bevy of wonderful changes to the core gameplay.