I had the common problem that I could do anything but start the game. However, I also couldn't uninstall the game. I have no idea where the files are saved (they aren't in the folder I told the downloader to save them to), and when I tried to re-download the client it just opened up the launcher again with the same problems.
My problem is that when I press the play button it has the loading screen come up for 1 second then it disappears and nothing happens.
IMPORTANT:Run the updater to receive new files and delete the file named 94.23.237.127.2238.cache in the data folder.In the FOnline.cfg file, find the line "PatchDatPath=fonline.dat" and change it to "PatchDatPath=faction.zip".DAT files entered deprecation stage, whenever a .zip file with the same name is downloaded, the corresponding .dat can be deleted. In addition, fonline.dat is deprecated.
Recently downloaded and installed FOnline, did the .dat changes in FOConfig.exe but I'm finding that it still isn't detecting master.datMoved both .dat files into the game folder which is under C:/Games which was the default.Also updated the game before trying to play.I'm running Windows XP (I think) Service Pack 3.Any help would be most welcomed and further info from my end can be provided on request.