I wish I could mod to create a hall of fame within Civ. The scoring doesn't seem that satisfying to me. I have gone for 2500 before and it was far from the best game I played. It was just a week long domination victory on epic where I improved my conquered cities.
I want to see a more robust scoring system that rewards better for wonders, subtracts points per turn, calculates scoring based on GPT, SPT, or CPT.
I also want victories by leader, the score and number of turns to be accessible. Some type of database so you can set goals for a game and victory conditon ideas for games.
It's just wholly unsatisfying to play a game and it's gone but I would imagine with an SDK this is a very easy thing to design and implement. We could do a better job than Firaxis and let them focus on the core game.