I loved Civ 3, and I loved Civ 5 right upon the pickup of the game. I didn't have the same experience with Civ 4 at all. I felt that a lot of the combat took a very long time to understand, and that religion muddled up diplomacy. Once I understood it, it was fine, but it had a large learning curve and I still didn't understand it well. I really disliked corporations as well. Civ 5 had the same pick-up fun Civ 3 had.