Well, I finished my first Marathon mode game. Got a domination victory in the 1600s. It now stands as my highest score. It wasn't bad once I got out of the early ages. I had to build up until I had Knights before I went into conqering mode. Prior to that, I had the most amazing thing happen. I founded Hinduism and at one point in history, every civ was Hindu, even Elisabeth, who had founded Buddhism. If I hadn't already said no to a few tech demands I would have thought about going for a Diplo win. I have never had so many folk like me. Then, just before I was ready to launch my conquering hordes. Various Civs started little wars with each other. The diplomacy screen was a mess of different colors!
For some reason, I felt it more necessary to micro manage things I had never done before. I am not entirely sure why that was. It is probably good for my overall game. I'll try a couple more Marathon games if I can. They sure do take up more real-time time. That is the major disadvantage so far. I have to keep remembering what my grand strategy was in between playing sessions.