I just got a score of 2012 (or 3006, if you believe what it says before sending) on a game that's pretty much about the end of a civilization, I bet that's what the maya's meant. Got the good start in 10 days, the tactician in 20 and final victory in 35, so the later achievements do seem to be easier to get, as others noted. (Or maybe that's because I bought only part of the units, that may be cheating) It did get a bit repetitive, but at least the gamespeed could be set higher, and the charge helped too.
Overall, it was pretty fun.