I would like to see a gradual planet terraforming that takes place over time. Instead of just clicking on a research item and being able to immediately colonise a planet type I would like to see resources being spent over time to gradually widen/shift the temperature etc to gradually create a more suitable environment. 


I used to play a game called Stars! and this was one of the better concepts in that remarkable game where each planet had a livable range and you could gradually change it over time to make it more suitable for your race.