The file extension SAV is generally used for so-called savegames, that is, games of various computer games. Sav does not represent its own format. Sav files can only be reloaded with the game with which they were saved. Often the version numbers or patch versions can not be different.
The content of a SAV file is of course different from game to game, but always includes information such as player's position, items, and progress, and often much more. The file extension SAV is used among others by Half-Life 2, Mount & Blade, Spellforce 2, OpenTTD and Dune.
For an unknown SAV file, it may be helpful to load it into a hex editor. Sometimes you can tell in the first lines to which game it belongs, if it is a savegame file.
Most often resolving problems with opening SAV files is very simple. Just install an appropriate program that supports such files. All of the listed programs support SAV files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of SAV files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate SAV files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the Original program applications is not on the list, select "Browse" option in order to manually locate the directory where Original program has been installed.
Sometimes problems with opening SAV files may not lie with the application itself, but can arise due to other causes, such as: