While Nexon no longer publishes Combat Arms, the classic version of the game along with the revamped 'Reloaded' version are available through their affiliate company Valofe (which also publishes another old Nexon title, Atlantica Online). While no word on whether Combat Arms classic is launching on Steam, the Reloaded version is headed to Valve's platform in the near future.
No word on exactly when the Steam launch is happening, but the game is available right now on its official website.
The original Combat Arms game launched back in 2008 and quickly grew in popularity. It was one of the first mega popular free to play shooters from South Korea. Since launch it has reached 1.5 million registered users and still has a core active community.