Why don't we have mid-game/end-game challenge as well ?

It could be fun if someone play the opening badly then people have to salvage it somehow as a challenge. This can be more challenging than the usual format.

hmm.. problem with Civ5 is that all choices are permanent. In Civ4 it was possible to take save and use your skills to drastically change course of the game. In Civ5 bad choice always stay bad choice.

There are no revolutions to correct problem or to push civ in right direction.

So, basically screw up save is screw up save..