just like ":)" or ":D" which expresses happiness.
Often (exclusively) used by Russians. Very often used in games as a way to find out who is russian and kick them before the start of a game to prevent certain lag and ping issues due to the far distance. Originates in Warcraft
Reign of Chaos or even Starcraft, where only Latin characters of the keyboard are displayed and
Cyrillic/Chinese and other symbols are displayed as empty space ( spacebar ). Russian keyboard layout on the " : " is an
cyrillic ASCII therefor not displayed.
Can be use with multple ")" for example ")))))))))" . Trends on and still popular, even though nowadays all languages are integrated in OS and Games. All Russian youngsters using it dont know its origins.