Some fun beelines: archers->machinery->metal casting for bombards+pike/shot beeline to feudalism for knights. Kill a unit with a knight for super fast cavalry Ancient walls to get engineering. Aqueduct to get military engineering. armory for gunpowder. Get a military engineer to pop a couple forts down and you have cuirassier/gattling guns (and Rangers with a niter mine) Getting your universities down to rush to printing press/astronomy 2xHarbor->Caravel (adding in lumber mill->shipyards->ironclads) Of course, we saw all this, but some of these are slightly dependant on terrain too. You can't rush for Rangers if you have no niter nearby. And just because you can unlock cavalry super early, if your cities are only getting 10 production per turn because it's still the classical era, that cavalry is going to take a buttload of time to build or upgrade into, especially since the 50% upgrade card won't come until normal.