Hi,
After a lot of experience 
I have decided to write a check list of things to try, in rough order of severity, that people can try when Galciv3 doesn't seem to be working. Please understand, there is also the Game Support FAQ, and this is not meant to replace it! But I have had some luck suggesting these things to others and have had others suggest things here on the board or elsewhere to me. As usual, there is no guarantee. IN ANY case that you have some doubt, try posting in this forum. Lots of helpful people to explain things further! Don't be bashful! We have ALL been there. P.S. I am NOT by any means a super guru or developer or something. If I can do it, I suspect everybody who finds this can also.
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(Note) If you find what appears to be an isolated bug, then try to document it and send in a ticket (see bottom below).
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This list is in case the game doesn't seem to work at all, or crashes a LOT, etc.
During the beta I have used everything in this list at some point or other to get
things working. Remember after each update or patch to be on guard. Any funny
business, try working down this list.
Sometimes Steam, or Windows, or whatever causes a download to not work properly.
Please note --> this is specifically for Win 7. If you have a later version of
Windows the commands in windows will be somewhat different, but you should be able
to figure it out without much trouble.
0 Assure that you are running Win 7 64 bit or later. Click Start, right click
on Computer->Properties and look at "System". This display will also show your
memory. Less than 8gb may present problems, as the game is not optimized yet.
If you are not 64 bit, you cannot run the game.
1 Make sure you have latest drivers. In Steam, click the Steam menu and click
"Check for Video Driver Updates".
2 Check your virtual memory. Start, then type "virtual" in the window provided,
and select "How to change your virtual memory settings", click to open System-
>Advanced system settings->Advanced tab->Performance->Settings->Advanced tab-
>virtual memory. You should have at least 4 gb of virtual memory (4096 mb in the
settings). I suggest making virtual memory fixed by setting max and min size
equal. Microsoft suggests making the lower bound equal to your current memory size and the upper bound 3 times as large, so if you have 4 gb memory, set the lower bound to 4096 mb and the upper bound to 12288 mb. For larger amounts of installed RAM, you actually can use smaller settings. At 16 gB, I use 256 mb lower bound and 2048 mb upper bound (as I have seen suggested). I have been told/discovered that turning off virtual memory with 16 gB or more memory to improve performance is actually a myth. (Thanks to kryo for this!)
Please note: Before you actually upgrade your RAM, you need to check (1) what your current operating system will handle, and (2) what your motherboard will handle. (Thanks to Blue_Oyster for this!)
2a If you have less than 8 gb RAM, consider adding as much as possible up to 16 gb. In some situations it is not terribly expensive. I was able to buy 16 gb of memory for my 4 year old Dell Studio XPS for $96, which will extend the computer's life a couple years, and makes the game run very smoothly for me.
(Thanks to LuckyJack for suggestions.)
3 Reboot your computer. It does help sometimes!
4 (Verify Windows File System) Click Start -> All Programs -> Accessories.
Then right click on "Command Prompt" and choose "Run as Administrator". In the
dos window that opens, type
sfc /scannow and press Enter
If any bad system files are found, Windows will automatically try to fix them.
If it is unable to, that's a bad thing. It happened to me, and I wound up having
to reinstall Windows. Unfortunately, if sfc is unable to fix bad files, you may
have problems with any application on your computer, so a clean reinstall is
indicated. Hey, it will help your computer run faster in many instances and it
will allow you to NOT install Windows features that you don't need. Of course there will a be some work to do!
5 (Steam file check) Verify integrity of the Galciv3 installation via right
clicking on Galactic Civilizations III in your Steam Library list -> Properties ->
Local Files -> "Verify Integrty of Game Cache". This takes a few minutes. If
anything is downloaded during this, you had a corrupt game file. Test Galciv3 to
see if this fixed it. If you get the message that all files were good, then no
corruption was found.
6 (Use opt in patch) right click on Galactic Civilization III in your Steam
library -> Properties. Click Betas and select the drop down menu on the top, then
select the opt-in. (If there is no entry, then no optin is available, so skip down).
Leave the space for Beta code blank, it is not used for these
opt-in patches. The download will be fast. Restart the game and check.
7 (Force local files to be consistent with the current version of Galciv3)
Rename your My Games\Galciv3\ folder, for example, to My Games\Galciv3.old. Exit
Steam, then restart Galciv3. Check the game. If working, you can try, if you want, copying
save games, etc. from the renamed My Games\Galciv3\ folder to the new folder just
created, then restart the game and check.
7a Similarly, you can rename the C:\ProgramData\Stardock\Galatic Civilizations III folder. This is by default a protected file, but you can change its permissions with administrator privileges so you can see and edit files in it. The game will then recreate necessary files.
If necessary you can find the ProgramData folder by typing %ProgramData% in the Windows Explorer address bar.
(thanks to Thecw for this)
8 (Full Galciv3 reinstall) In your Steam library, right click on Galactic
Civilizations III -> Delete Local Content. Exit Steam, then restart Steam and
from the Steam Library, install Galactic Civilizations III. Check if it is running
ok.
9 Delete everything in your Steam folder EXCEPT steamapps folder and steam.exe.
Run steam.exe by clicking on it. It will recopy all of the other Steam files.
Test the game.
10 (complete Steam reinstall) Copy your Steam\SteamApps folder to a temp space,
such as the desktop, then uninstall steam using Control Panel->Programs and
Features->Steam, and reboot when finished. Then reinstall Steam (do an internet
search for "Steam download", for example), check that Steam seems to be working.
Install Galciv3 from the Steam library list. Check if it is working. Load the optin patch if there is one.
If the game seems to be working, consider copying files from your Steamapps folder backup to the new Steamapps
folder.
->->->
If you are still having trouble, or anything I suggest sounds confusing, definitely head to
https://forums.galciv3.com/452855/page/1/
for instructions on how to submit a ticket. Note, your forums username and
password will not work for the Stardock support area; you need to establish a
separate username and password to submit and monitor tickets. I STRONGLY
encourage you to do so, as it gives the developers the data they need to fix bugs.
This helps everyone!
Addendum:
I ran into a nice and fairly short presentation on ways to help your computer run more smoothly. You may wish to check it out. One nice idea was using the task manager to check if background programs may be causing issues. Please note as stated above that the comments in this video concerning turning off your paging file if you have 16gB or more memory is outdated. (See above).
https://www.youtube.com/watch?v=qpqk3qrRIrQ
Good luck!
