Space race (Cold War) gamemode
So this idea is from the space race, you and the AI compete (lets say KSP but you have the lowest research stuff, money etc) and you have to race against the AI to get to the moon first.
This will last can last a long time, as you have to plan how much money you will spend for research etc. or doing contracts (the one in KSP, if it gets implemented here).
Their will be a difficulty option aswell.