Pk2 extension is associated with Silkroad Online Game Data File. These files can be opened by XVI32 hex editor.

Silkroad is a multiplayer game. These type of games called MMORPG (Massively Multiplayer Online Role Playing Game)
Silkroad is a South Korea based and the system files which found in this game use PK2  extension. Game graphics and the sounds are found in pk2 files. Because it is a compressed file type, you are not able to take a look to these formats with regular opener softwares. 

However, you have chance to make some changes on these files with XVI32 hex editor program. Please be careful that you back up the file before making any process on it. Because if the file is corrupted, you can`t open the game again.  You have chance to get detailed information from the following web pages.

What to use pk2

XVI32 hex editor

which page related to pk2 file\r\n

pk2 Related Searches

You can check related links about pk2 fileextension.