I want to also stress what Crayton said. Each civ takes up X ammount of room in memory, and in Civ IV this is larger than ever before. If you look on the map a GREAT deal of extra numbers are kept track of than in any other previous incarnation. Soren and the rest of the Firaxis team put 18 as the limit FOR A REASON. It is not because they are lazy. It is not because they hate you. It is because the number of computations would triple from the levels they are already at and consume more ram. 3D has little to do with this specific issue. Had the game remained 2d sprites they would still have the same issues. Let me put it to you this way. Had they made 31 civilizations playable even if computers would not have been able to run it you would have complained that the game was buggy and unstable and that they shouldn't of had so many civs playable. And here is my final point. THIS ISN'T YOUR GAME! I made similar comment to people who had problems with the content of The new star wars movies. They felt that abc shoudl have hap[pened instead of xyz. If they wanted to have a story (on in this case a game) with particular features then make it yourself. Is Civ IV perfict? Nope and they are already working on patching it I'm sure, but don't cry because they limited the current playable levels to 18 civs.