As far as diplomacy goes, there are both internal and external forms. There’s a straight-forward diplomacy window you can open whenever it’s your turn to enter negotiations with any other clans you have encountered. This window is quite similar to the one found in Civilization games. Here you can make offers and counteroffers, anywhere from declaring a peace treaty or declaring war to demanding or offering hostages of a clan’s ruling family. You can strengthen your alliance with another clan by arranging a marriage between the two families, or you can set a clan against another by agreeing to a peace treaty only if they declare war on one of your enemies.
When you attack a city or another army, you get two options for how you want to progress with the battle. You can auto-battle, which has the computer weigh the strength of the two forces and declare the outcome, or you can take it to the battlefield for the RTS portion of the game. I’ve dabbled a very small amount in this part of the game - enough to know it’s challenging and suitably complex, but I’m by no means an expert at it. Part of this is because the campaign map portion of the game is more than enough of a game by itself (trust me, gaining control of all those territories takes a ton of strategy and time without worrying about actually fighting the battles as it is).
UPDATE: While I originally thought that co-op isn’t always fully supported on the battlefield, this isn't really the case. When your army clashes with another army and you decide to take it to the battlefield, at first it appears that your co-op partner can spectate the fight, but won’t be able to actually participate as he or she has no units invested in the fight. However, you can gift some of your units to your co-op partner so they can play with you. There is also the potential opportunity, for both of your armies be on the battlefield: when one of you is reinforcing the other one in an attack against an enemy. To do this, however, your armies must be pretty much right up on each other on the campaign map when one of you attacks. For my and my partner’s play-style, mirroring our armies seems ineffective, so we skipped this option. We were having an excellent time purely playing the game on the campaign map. Though some die-hard RTS’ers may disagree, I think the auto-battle option is a great idea so people have a choice between a pure strategy game and a strategy game with real time strategy battles. It really opens up the game to a wider group of players.
I only really had one other small complaint with the game, and it’s mostly a complaint inherent to any turn-based game played cooperatively. During the turn-based portion of the game, you and your co-op partner each have your own turn. While you certainly aren’t stuck not being able to do anything at all during your partner’s turn (e.g. you can check out all your cities, queue up recruiting, browse the in-game Encyclopedia, etc.), there were times where I found myself out of things to keep myself busy with. Again, this was pretty minor, and many potential problems surrounding this could simply be cleared up if you and your co-op partner are courteous of each other and try to make your turns as quick and efficient as possible.
In conclusion, Shogun 2: Total War completely met my expectations and even exceeded them in some areas. I still feel as if I’ve barely scratched the surface of the potential depth of the game. The great thing is that you can get by with the basic knowledge, but greater potential is there if you want to pursue it. For example, I’ve hardly experimented at all with the monk agents, but if I chose to utilize them more, I’m sure I’d be well-rewarded for my effort. There’s a ridiculous amount of time you could sink into this game and it’s infinitely replayable. If you have any interest in co-op strategy games, Shogun 2 is an extremely well-crafted game with impressive graphics and an astounding amount of depth.
The Co-Op Experience: In a co-op campaign, you each get your own families (so you can make your own choices about your tech trees and campaign characters), but your families are automatically entered into an alliance. The win condition is either one of you becoming Shogun, and we were assured that there is no backstabbing allowed in this alliance. It sounds virtually the same as the single-player campaign mode except you're working together to win the game instead of just you on your own.
Co-Optimus game reviews focus on the cooperative experience of a game, our final score graphic represents this experience along with an average score for the game overall. For an explanation of our scores please check our Review Score Explanation Guide.