Far Cry 3 Sound-english.dat And Sound-english.fat Files - Google Link

Far Cry 3 is built on Ubisoft's proprietary Dunia Engine 2. To keep the game's directory organized and to protect assets, the engine packages game data into proprietary archive files. The two companion files you've encountered are the most common form of this packaging system:

The main sound.dat file (without a language suffix) is the primary archive for the game's universal sounds and music, while the language-specific files like sound_english.dat contain the voice-over dialogue. Similarly, other folders like worlds\fc3_main\ and worlds\multicommon\ also contain language-specific .dat and .fat pairs for other game assets. Far Cry 3 is built on Ubisoft's proprietary Dunia Engine 2