My first game was on hard, and it was interesting. Getting to the center was very very tough (and I was a Knight, max health of 1500) and took a lot of reloading. Civ was pretty scary for me - economic, and on hard it seems the military quickly trounces any of the smaller empires (little hint - don't buy a city that's under attack, you become at war with the other nation then). So, there I was, with one city while the other civs fought and killed and grew and expanded and got planes - it was down to me with one city, and 3 other military civs. One was on my continent, the other two on the big continent. I paid off the other two civs to attack the one on nearest to me, bought off one of their cities, and took all their spice derricks. I was able to buy out their other 2 cities, kept one as military, and by that point I had a good amount of income, so I could build a giant army that I used to crush each of the other opponents. Very tough and nail-biting, but loads of fun.
Tribal was fairly easy for me, I allied with the first two tribes, killed off the rest (I had the animal master tool, which is great to use on a group of animals, and send them and your chieftain to create a diversion while your army goes in for the kill on the rivals.
Those were my experiences on my first hard game. I'm now starting my second, and I'm in creature. Oh, and I'm doing it without eyes. Very challenging so far.

-m.