And deranger and I promised to comment on the intresting situation that emerged in turn 5:

(Or replay the whole game using the first link).
The question is: Was it good for Tyrell to attack Martell here?
I was Tyrell and decided to attack deranger (martell) for following reasons:
1) In previous 4 turns I tried to agree on a strong pact with Martell I could trust. But he never committed to it clearly and his wordings were always unclear. Alliance yes but no strong brotherhood if you see what I mean.
2) you can see both Bara and Martell played CP on their border in turns 1-5 which makes it clear that Martell made a deal with Bara too. And he just wants to power and wait with a view to stab either bara or tyrell when the weakness opens.
Conclusion 1: I could not have relied on south alliance too much. I dont blame Martell for it. That was just a fact.
(As an interesting side topic I think that in games with good players it is generally bad to be too opportunistic / double faced. Good players will see through the farce and will not trust you. Just pick one ally and work with him. Thats a better start, especially between Martell and Tyrell).
3)Tyrells way north on land is blocked by bara-lanni alliance on land. Bara has a huge support in Blackwater and can always raid Reach first due to higher throne position. So if younwanted to go north on land as a Tyrell here, Bara+Lanni have a message for you: "You shall not pass!!!"
4) So how about being Standard Tyrell and crush Krakens on sea??
It does not work either because of two reasons. First Greyjoy is aware of that option and manages his cards carefully. Secondly if I bite into GJ now it just gives Stark a complete freeroll. Whilst we squable around Sunset sea raiding and attacking/defending adjacent territories, Stark will grow stronger and snitch the Greywater watch which is a key to both Seagard and Flint later.
5) Stark is already too strong.
6) in this round Bara clearly wants to take Reach out of me.
7) and Martell wants to Doran in Kingswood and take Shipbreaker bay. That is a controlling disaster for two reasons: number 1 Stark gets a sword to further bolster his winning freeroll. Number 2: Bara is crippled and it makes CCP easy target.
Conclusion 2: Going north and sticking to questionable Martell alliance makes me lose Reach and produce 3 upsides for Stark: sword; easy targets east; easy targets west
So I did a deal with Bara to not take Reach and become friendly with me if I save his ass from Martell.
This generated 3 big upsides for me as Tyrell:
1) Stark path to victory (which was already likely anyway) did not become easier.
2) I earned a good Bara ally and did not lose reach.
3) I got a leg up in fight vs Martell.
Deranger was passionately telling me that it was wrong for Tyrell to attack Marty here. I have respect for good players on the platform and like to learn from them, so I said I would post my thought process and hear counter arguments.
Game is in turn 10 now. It looks that Stark is likely winning anyway but at least there are some chances.
Happy to hear your opinions

It should be anexed with zizzeus guide eheh 
and you were already one of the top players on this website. And you stabbed bara one round later too! You didn't do it because of me being allied with bara too. You did it because you saw a chance to stab me and an opportunity to convince bara to help you. I was naive to be allied to both but those were the times I still officially announced breaking an alliance 1 round in advance
). You could have an alliance with one and a truce with another, or a truce with both. And you could also have alliances that only lasts a certain number of turns. Martell might conclude that his best bet is to be passive for the first turns of the game. Why not strike a non-aggression deal with Baratheon in this case?