I recently played an amazing DOS game where you have your country and you can declare war or peace with other ones, and i really enjoyed it. Growing up one of my favorite DOS games was Gobliiins 3, such cool memories!
Space Hulk would definitely be mine
Star Control II for sure. Fantastic game, still one of the best story-based games I’ve played. Heavily inspired a lot of more modern franchises, too, including Mass Effect.
Wing Commander Privateer - I love a good economy game in my spaceship game.
Mechwarrior - Battletech 1st person. Get you a 30 foot tall robot and shoot some lasers at other giant robots. Go for the knees.
Wing Commander 2. My Dad sourced it and the manual was a B&W photocopy. It took ages to get onto it sometimes as the photocopy was so bad I’d be unable to decipher what letter 6 on line 8 of page 10 was.
Dune II: The Building of a Dynasty, but I’ll give Wolfenstein 3D an honorable mention.