It would have a very motivating effect, if a highscore list could be implemented.
In ironman mode, it would be great, if you can get a new highscore, instead of loosing the game and be dissappointed about it.
In my opinion, this little feature could have a very great effect on motivation. So you love to start a new game in ironman and try to get a new score.
Loosing a game without any history of it (only a small score at the end which is nit saved or listed anywhere) is very frustrating.
You could include the final score, how many kills, how many lost brothers, how many days your band was alive and what great efforts your boys have made.
(Killing the big beasts, won a crisis etc.).