I am new to the game so maybe I have a different perspective on the game as viewed from a brand new player but one thing I found missing from the start was the ability to replay a same map at higher difficulty level or with different opponents.
I would suggest a "save map" feature, that would only save the actual stars system and planets (maybe anomalies as well) but without the ennemy races (and AI difficulty) and their starting positions. This way you can replay a map you like with different tactics or different opponents.
Just my 2bc
Ducky