Anyone plays rise of nations against computer players ?
I figured out some interesting 'feature' yesterday. When playing against computer players only, try staying in the Medieval Age (or some other age). The computer players will never pass you in age reaserch. Even better, they seem to only do a certain amount of other library researches per age. So you can research all of your library researches, but only advance 1 age, and they'll be stuck at that 1 age + 1 library research per category.
It's weird. And it doesn't work in world domination campaigns. But solo, it can give you a huge advantage ... Which in fact isn't cool once you know it.