For me it's gotta be global warming. It's always been a lame mechanic but this latest bout with it was so lame I had to post it. Was just playing a nice OCC going for Space (possibly diplo if stupid Suleiman would just demand one or two more techs from me to get to friendly) and in 1900 Pericles and Suleiman have a huge nuke shootout (probably 15'ish Strategic Nukes and 30'ish Tac Nukes in total). Guess where ALL the global warming ends up when I've got a 1 part lead on the next closest guy in space race!!! My Fat-X!! Despite the fact I have 10 forest preserves (plus some more outside the Fat-X to have a few little forest growth/chop areas) and my super-eco friendly territory should be the last place on earth the actual crap occurs. Within 10-years (marathon) I lost 6 tiles from my Fat-x, (3 farms, 2 grassland forest prerves, and an Aluminum mine). At that point I had to Alt-F4 and say 'F*** YOU CIV' until tomorrow. I'll reload pre-war and see if I can avoid the bs somehow. What are some of the things that make you have to Flip your old buddy Civ the bird and shut it down every once in awhile?