@Kevin - I made a scenario using Ghengis Kai's GEM with modern resources last year (210 x 90 = 18900 tiles). It didn't last very long. Half way through I didn't like the feel of the map but was too lazy to change so I went through with it. The result is some +400 cities and +3000 units. Though it did feel a little "epic" it didn't run too well. I also didn't understand why it randomly crashed during Hotseat multiplayer . So this time around I decided to use Carter's map (192 x 120 = 23040 tiles) simply because it "looks better" but with a little hesistation because it's has 4000+ more tiles. However the result is much better since there are much less land masses. (only 275 cities and 2000 units). And it hasn't crashed.... yet. I'm not sure how yours will turn out though. Try to put it in a modern scenario and see if it crashes.