Lords of Midnight is widely regarded as the game that sparked the Epic genre movement with its mix of Adventure and Strategy genres but on a scale never before seen in the mid-'80s. With thousands of scenes and a map with thousands of locations, it's a wonder how the game ever fitted on a cassette and ran on a ZX Spectrum.
Doomdark's Revenge took the concept considerably further and dwarfed Lords of Midnight in scale and was the game that encapsulated strategy game purists at the time. If you have played games like King's Bounty, Heroes of Might and Magic and even the larger 4x games like Civilization and Stellaris, then you'll understand the scale of these games and what their accomplishments were.
While I have not played either of them, I am an avid 4x player and owe a lot to these games. If you're interested in picking up these titles then you can get Doomdark's Revenge and Lords of Midnight over at GOG now. How long they will be available for free is unknown so get them while you can and take a dip into gaming history.