I think a good idea would be to sell the manual by itself. I for one like to read in bed before it's lights out and I like to read my game manuals in addition to magazines, etc. Selling the game manual by itself would allow that.
One of the very first games I ever played on the first PC I bought back in the mid 80's (yes I'm old) was Starflight and later it's sequel Starflight 2. They were rpg's where you explored planets, interacted with alien species, fought battles in space and on the ground and just generally were great games. I would looooove to see a remake with all the whizz bang computer power available now. Stardock could pull it off I think.
I really like the person's idea on mayors for cities. Methinks that after playing a large game city management would get bogged down quite a bit. Also some buttons to direct the mayors as to what to build, ie; production, research, population, soldiers; you get the idea. Some resources that were mentioned, gems, different types of trees for different weapon types, wild game, etc, I believe would be great to have. Also lets don't forget about resources in the ocea
I would come down on the side of more customization. Fiddlin' with stats, tendencies, body types, etc. is what I like to do.