I dont know if anyone has posted about this before, but there is a way to really use those Mutual Protection Pacts to your advantage and take over the world with them. You can even use them to the same effect as a military alliance.
Currently I am using this on a standard size map on regent level. The situation is that there are 2 large continents and only 3 small (10 squares or less) islands in the game. I (indians) started on the same continent as the Chinese, Japanese, Persians and Zulus. Meanwhile the English, Germans and French are on the other smaller continent.
For the first part of the game I played very peacefully, trading techs for huge per/turn sums with all the other civs. This kept them happy enough to not attack me. But once I was secure in my tech and industrial lead it was time to start the plans for world domination. My tech lead is good enough to allow me to keep the newest 4-5 techs to myself and then trade on older one everytime I get an advance. The revenue from trading has allowed me to keep science at 80-90% most of the game.
I could have beaten the chinese alone, but why waste resources and risk a backstab from another nation by having a long war? Besides, as a democracy I need to finish wars fast to keep the people happy. So I signed MPPs with the Persians, Japanese and Zulus, thus isolating my dear neighbours the Chinese. Then I declared war on them! Before doing so I had fortified my entire border with defensive units so they couldnt get into my territory. The chinese had MPPs with some of the AIs, so I had to make sure they werent activated. The trick here is that MPPs are not about who declares the war, but rather about who attacks the other guy within his own borders. So I sat back and let the chinese come to me. The moment their first Rider attacked my border they had 3 other civs declaring war on them. Within 10 turns they were gone and I got about half their cities with my 3 allies sharing the rest.
I have kept this going by eliminating the Zulus with the help from all other civs and then the Persians. Since all the remaining nations are my allies in the war, this "salami-method" of conquest doesnt hurt my reputation and I make sure to finish off the civ I am at war with (if I dont do it, one of my allies will
). My next target was going to be the Japanese to clear out my own continent, but then the germans built the first piece of a spaceship and I had to take their capital (again with the help of the 3 other remaining civs
). Its now year 1800 and I have my spaceship built, but I wont launch it now beacuse I want osee how high I can build my score. This means I have to prevent my opponents from building their ships, but I have allready taken control of more then 50% of the worlds resources. Only the Japanese have any uranium and they lack most other resources needed for the ship. And should the 3 remaining civs trade somehow to let of of them build a ship, I have enough military to fight all 3 at once if necesary. All because I have conquered 3 civs with a minimum use of force, allowing me to build up my cities and tech instead
