Germany forward settled and DOWd me before I hit construction; I held them off with Companion Cavalry and Archers, then continued the war conquering North to Berlin (4 cities).
Went West
and I believe took out the Huns before I hit Machinery (Edit: got Machinery/XBows right before I DOWd the Huns). Made sure everyone passed by the Fountain of Youth as I took on the Celts next (they were very weak).
South to St. Petersburg (Great Wall), waiting a couple turns for DOF to expire; took that city and Moscow, made peace, then right into the Romans: burnt their city N of Moscow, puppeted the one between Moscow and Rome. Left the Romans with their 2 cities N of Rome and DOW Russia again, taking Novgorod (S of Moscow), which had built up an army, and 2 cities to the NW that were on my way to the Mayans.
I was friends with the Mayans and Polish for a long time; both ended when they denounced me.
The Polish had a huge number of troops around Palenque, mainly their UU horse, but weren't doing any damage. I could only get a few XBows (with Logistics and Range) within range of Palenque and very slowly wore it down, them moved troops towards Warsaw. During this time, I built up some Canons/Artillery and moved them in from Berlin through Wellington (Allied Wellington and Kiev shortly before attacking the Polish).
Upgraded to Gatling Guns as I moved into Warsaw. Lost some troops but had plenty and it was just a matter of time as, at the end, I had 7 Logistics Gatling Guns within range of Warsaw and 7 Artillery coming in from the West.