In virtually all linux distros you have a resolution that you can choose from using some form of config utility. In FC1 it is called Display. This utility sets the resolution of the desktop in accordance with the monitor and the graphics card. It does not give you the choice to specify the refresh rate although it will write the “believed” refresh rate to the XF86Config file (or XF86Config-4, or xorg.conf–whatever your distro is using).
On top of that a desktop interface may permit you to specify the resolution, color depth, and refresh rate from a list (KDE 3.x does). These are options provided within KDE as per whatever you selected and that which was written to the XF86Config file. In otherwords KDE won’t allow you to select a resolution, color depth, or refresh rate higher than that which is listed in the XF86Config file.
The same would seem so with most linux games, including unreal tournament, army ops, quake III, ET, etc.
In order to ensure that you are running the game full screen you need to ensure that your X is configured for the resolution you choose. You must also ensure that you haven’t used KDE to choose a lower res or you will be forced into a window.
So, make sure KDE is set at the resolution you want and remember that you will only be able to play the game full screen if you choose that resolution (or a lower resolution than that).
So, if X allows for 1280x1024 then you can select 1280x1024 in game. If you choose 1600x1200 you will force it into a window. If you set your desktop to 800x600 and try to run the game as 1024x768 then you will see the game in a window. To play the game in 1280x1024 or 1024x768 you need to run X at those resolutions.
If you have your desktop at 1024x768 and you want to run the game at 800x600 that is fine. It will run full screen. But…you’ll not notice much of a difference in the looks of the game.
Alt+enter makes no difference unless the resolutions are the same or the game is run at a lower resolution than X is set to.