Posting a bit late, but me and the family were heading off for a week's vacation very early May 1st, so I quickly finished the game and submitted. Originally planned for 20K, but had to punch out a diplo game just to submit. My 20K wasn't going that great anyway.
Just a few comments: founded capital to SE, and Pyongyang my 20K city N-NE of original spot, which is a shield rich space, with access to both Game and Cattle to support all those mountains tiles, but no fresh water so no free aquaduct. This makes Construction very important, and it might have been worthwhile to take it for free after learning Philosophy. I took a free Republic, but being stuck with a size 6 city in Republic might not be as good as a size12 in Despotism. Just a thought.
Originally planned on building 5 wonders, but only built 3 and missed out (of all things) Colossus and Great Library! Yikes! Didn't get GA until beginning of IA with Smith's. Early GA - good, especially with all the Wonders in C3C!
Did good with the MidAge wonders. AI built Sun-Tzu's and Knights Templar (ok), and a second city of mine busted up the cascade by completing Leo's before Astronomy was widely known. So I built the rest except Magellan's which they just beat me to.
Having Coal was very nice; lacking Rubber and Oil took some work. I took over the marshy island with Oil. And Carthage had both resources; you don't need Rubber for Guerillas and Artillery, and they work just fine together against medieval armies, which Carthage had.
Carthage bought the Celts in against me; they'd taken Rubber island, so I got a 2nd source there. And it seemed the AI wasn't keen on attacking Cavalry against Tanks (by this time), so I was setting up a Funnel-of-Doom with Tanks (like SirPleb did with Armies) to create a serpentine path for Celtic cavalry to pass through, causing them to lose hitpoints from the Tanks' ZOC, and making them easy leader fodder. (Finally got a GL, but I'd already run out of time and was getting a UN vote set up.) Older Techs got everyone allied vs the Celts; Brennus was the other candidate and it went 6-1 in my favor.
Very, VERY devious map, Karasu! Thanks

; this was fun and I'm glad I played it.