Game Settings control a huge number of things in the game. Formulas for damage, AI, potion strength, all use GMST's, as they are known, as constants. Many of the names and titles in the game are set by a setting, and very little of the game is completely independent of them.
Game Settings may be changed in the Gameplay->Settings menu, or they can be changed by script using OBSE's con_SetGameSetting and SetNumericGameSetting functions. Even without OBSE, Oblivion natively provides the GetGameSetting function, allowing scripts to take advantage of these settings to enhance compatibility with other mods.
As you can see, there are hundreds of game settings (aka GMST's). Some are relatively innocent, such as fSneakSleepBonus, which determines the Sneak bonus an actor gets if the target is sleeping. Others can break the game in a heartbeat. Be very careful with any changes you make to these settings.
Note to Editors
Please remember to add new pages to the settings category by including the following code in your page:
<div id="catlinks"><p class='catlinks'>[[Special:Categories|Category]]: [[:Category:Settings|Settings]]</p></div>
If you don't have the full information for a setting, please remember to edit the template containing that setting so that others know it still needs updating in the same way as it is done in the following example:
[[fAbsorbBoltSmallWidth|<span style="color: #f00;">fAbsorbBoltSmallWidth</span>]]
Floating Point Game Settings:
Integer Game Settings
String Game Settings
Conceptualized Settings by Subcategory
This category has the following 9 subcategories, out of 9 total.