First, I'm not sure it's Serdoa. We only have the color to go by - there is no contact in game. I don't know if
the colors on CivStats tell us anything. Serdoa might be the best fit if that color of blue is matched with the border we see. Why it doesn't match the scoreboard in game is a mystery to me.
If it is Serdoa, I've never played with him but he has the reputation as one of the best and savviest players on this site. He also has a very short fuse, apparently.
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Among him, Plako, and Commodore he's one of the worst neighbours we could have drawn.
Yeah, we won't see graphs until 43 EP, 11 turns after contact, assuming we're both spending on each other to the max.
Warrior before worker doesn't appeal to me at all. I think it's more likely than not he either knows he has a close neighbour, or will by turn 15. If it fails it just means we've sort of spoiled someone's game and, our own even worse in turn.
Without sacrificing too much (maxing the hammers away from the silk tile, but still working improved corn as soon as it's online) we get warriors on turns 15, 20, 24, 26 if we build them straight. It does sacrifice something though - we grow to size three on turn 23 instead of turn 21, and also lose the beakers from not working the silk at all.
My gut is that he'll know we're close, with chances about 80%. There's no way you'd choose to go long with a settler in an 18 player game with land on all sides, without being aware of your immediate surroundings. Also I'd bet against him taking 15 turns to build a worker, as I bet most have settled on plains hills.
My personality says play normally and be careful. I also fear the kind of game we'd have to play for months after failing with a rush. But I'm arguably way too nice.
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There's a chance we have a big intelligence advantage right now, also a chance we both think we know something the other doesn't, etc.
Now, if we did a double warrior march starting on turn 20, is there a chance that works? I'm not sure about that. If he doesn't know we exist, maybe. A big factor is whether he has a hill in his culture (NE or NEE of his capital) that could spot our diagonal approach. Having three turns to react would be massively better than two turns.
Anyway... at the end of the day I don't think I can be convinced on a plan that doesn't finish the worker right now, so we have a bit of time to decide what's next. Presumably not making contact now is a no-brainer? (I wouldn't want to give up our advantage if he doesn't even know he has a neighbour net.)
I'm really not a fan of the scout choke in general. It makes enemies, doesn't actually gain us anything (beyond a slightly set back neighbour) and declaring war hurts the value of trade routes later, maybe. Plus I'd rather have a scout actually scouting.
The other question is can we afford to keep going with Meditation? If we do so, we get bronze on T36, wheel T43 (approximate). We can take 8 turns off of those if we switch now.