I'm in the middle of a game with Peter on Immortal difficulty. Luckily enough I started with Khmer and India as neighbors, not the most aggressive. I managed to found Vodkaism to get some bonuses. Khmer attacked and nearly wiped me. I exploited an Emergency against India that had converted Vodkaism's holy city, had to censure their religion from my city. It was easy enough and got me like 9000 gold, which I used to counter attack Khmer and annex the most part of his empire. Built a few Wonders, incl. Basil's Catherdral which sprung me up on the score ladder. I've been rollercoasting between normal, golden and dark ages, and just got a Heroic one, just in time to counter Jadwiga attacking from the north. Even if technologically late my Cossacks are pretty badass, being inflated with lots of experience earned from the Dark Age policy card which gives +100% combat xp. I'm preparing to use my Golden Age Casus Belli to cripple Ghandi and get closer to Poland. Meanwhile I am second in culture and tourism (only behind Poland), piling up great works and, I hope, more relics. All in all it's a nice game, I don't think I can catch up on science (I'm in mid-Industrial) but I'll try to hurt Poland and steal her great work and wonders towards cultural victory.