One thing I think needs fixing is the absence of high end stuff at the end of the tech tree. No stratosphere paratroops or giant robots. It means that once you have researched all the tech you need for your space programme, there's nothing new to get, and in the turns while you put the Mars mission together (a) the other civs catch up with you in tech, and (b) you just spam a lot of future tech. Science and culture become effectively useless commodities. I don't see why future tech has to be so useless. A few extra points on your score isn't going to make much difference. Future tech is not going to be as dull as, to steal a joke from Rowan Atkinson, inventing an Opal Fruit that tastes of fruit. It should have some tangible effect! I would suggest something like this: for each batch of future tech, all friendly combat units gain +5 combat strength. For each batch of future civ, all friendly cities gain 1 amenity. Maybe this would be an easy mod to make?