This should be as consistent as possible with the game-setup gui presented right before the game begins. There could also be a button which, after a warning and confirmation, could make some of the fields editable.
Game type, type of players (human/AI plus AI's difficulty), player colors, enable/disable fog-of-war, replenish land resources (there should be a similar option in setup screen to adjust the difficulty of the map), etc.
For example, when I win a game, I would like to remove fog-of-war, so as to see the remaining enemy empire without needing to destroy it or to send scouts. Or when I see that I have gained the upper-hand, I would like to exchange seats with the enemy, for a new challenge.
There could also be a button for destroying half of the player's empire and adding one or more new opponents with only one building but plenty of resources in it (plague plus sudden invasion). Or convert half of the empire into a new enemy (civil war). The point is to increase the value of an ongoing game and even give it some sense of flow in History.
Type of game (the win condition) is already shown in the objectives window.
> For example, when I win a game, I would like to remove fog-of-war,
This is something that i want also. But not as a button, it should be done automatically. And maybe not only if i won a game, also if i had lost a game. So it will be clear that the game has ended... somehow. Remind the bug 1556393
Ah, so you want buttons to change functionality - I though you wanted to edit some text fields. Yes, that would be nice - we need to refactor the win conditions first though, so that would be a separate bug as kaputtnik said.
This should be as consistent as possible with the game-setup gui presented right before the game begins. There could also be a button which, after a warning and confirmation, could make some of the fields editable.