Then why did you start it in the first place? Ah, to have fun. Then plan it better and do it right. Dont start halfhearted and make it worse by not even finishing it. Or if you want to fool around, then fool around on lower difficulty levels. The AI is a bad mofo from Monarch and upwards. Basically you are blaming the game for your bad strategic decisions. If you play with 18 civs on a standard map, you can expect each empire to be kinda small and packed... so if you want to war someone, you should be ready to lead the war to the bloody end. If you would have played on a larger map (or with less nations), the cities would have been more numerous and farther apart and cultural pressure wouldnt have been as powerful in the border regions (heck, with these settings there arent any border regions or outskirts at all! Everything is main land, so to say ).