Civilization 5 – How to Create a Pitboss Game?

The most critical part of your choice is "Does your graphics card support directx-10 (or 11)?"

If your graphics card does support higher versions, its usually best to run with the most recent version, to get whatever bugfixes, feature improvements (advanced lighting I believe) and performance gains.

Naturally, if your card does not support the higher versions, you should NOT try running the game in that mode, and stick to Directx9 instead. As StrixVaria says, running the game in that mode should simply not work, (that is what not supported means after all) but the best you can hope for if you do try is broken graphics or the game crashing.

As you've said, there does not appear to be any kind of "Automate City" or "Leave Forest option" available either in the game or in any config files.

UPDATE: The recent patch (around 10/28/2010) has added "Workers leave manually built improvements" to the in-game options menu. All you have to do is start the game and steam will download it for you.

As you've said these options are not available from within the game. Based on my research, sadly, both "Leave Forests" and "Automate City" seem to be completely missing. However, you can switch on "Leave Existing Improvements" by editing a config file.

There's some small chance that this option also forces them to leave forests, but I have not tested it in the slightest. If anyone else does test it please let us know!