Just tried a serious REX+ICS strategy for the first time. Launched the spaceship on turn 199 (1370AD iirc).
This was Emperor/Pangaea/Standard.
It wasn't really the policies that dominated, since I hardly bothered with culture at all. I picked up 4 policies in Liberty and that was it for the rest of the game. After that, my Social Policy costs were increasing faster than my culture. The ridiculousness came from raw population (Science!) and the trade route income.
I was packing cities at max density with no regard for terrain. Workers built luxuries, then roads, then farms. The trade route income was absolutely obscene. After turn 80 or so, I had stopped training settlers and was purchasing two every three turns. By turn 120, that was three every two turns. I'd temporarily lose a city or two from an AI DoW, but the overlapping city crossfire eliminated any danger from invasions. I'd rush buy a few military, retake the cities, and keep expanding like nothing happened.
The cities built nothing but a Colosseum and Library. Once the first few expansion cities were finishing their Colosseums, everything snowballed.
Unfortunately, playing the game this way was extremely dull. I was extremely excited about Civ 5 reducing the amount of time each late-game turn would take, with puppets and whatnot. ICS is a total reversal of that. You spend a very small amount of time early on making important decisions, and then spend a ton of time later on managing inconsequential crap.
The last thing I managed to research was Nuclear Fusion. It took 1 turn. I researched all of the Future Era techs in 1 turn each. The entire rocket took 11 turns to construct.