Civilization V: The Celtic Chronicle, part 1 (4000 B.C. to 1150 B.C.)
I'll be playing as the new Celt civilization, given that they are the second most awesome civilization in history (after the Vikings, who I have already played dozens of hours as in vanilla Civ V.) Their special units are an early-game spearman replacement, the Pictish Warrior, which grants Faith with every unit it kills, and the Ceilidh Hall, which replaces the Opera House and grants Happiness in addition to Culture. My strategy is to have a dominant, aggressive military in the early game to build faith before transitioning into Science and going for a space race victory.
I picked Continents Plus (easily my favorite map type), building a cold, wet world with a high sea level. I'll be competing with 11 other civilizations and 24 city-states on the Prince difficulty (which gives the AI their full faculties without adding any "unfair" advantages such as higher starting resources or clairvoyance.) Epic game length is my go-to, giving plenty of time for cool stuff to happen within each era without feeling like it takes a real-time century to get anything done.