Counter-Strike Nexon: Zombies, a free-to-play version of Valve's famous first-person multiplayer shooter that adds zombies to the mix, will release on PC via Steam September 23, according to the game's product page.

As you can tell from the images above, the game is based on the original Counter-Strike engine, not the later Counter-Strike: Source or Counter-Strike: Global Offensive iterations. It will feature traditional Counter-Strike modes like Hostage Rescue and Bomb Diffusion, as well as new PvE modes. These "Zombie Scenarios," as they're called, will include boss fights, unique player abilities, and more. There are over 20 different modes, 60 maps, and weapons that you won't find in other versions Counter-Strike. There's even a crafting mode that allows you to improve the weapons you own or create new ones.

The game is based on Counter-Strike Online, which was released in 2008 as a free-to-play game in Asia, but offers new modes, characters and weapon customization options that according to Nexon make it significantly different than the original. The most recent entry in the core series was 2012's Counter-Strike: Global Offensive, which is currently available for PC, Xbox 360, and PlayStation 3.

Nexon is also publishing Gears of War creator Cliff Bleszinski's upcoming free-to-play game, which is under production as Project Bluestreak. Counter-Strike Nexon: Zombies is also coming to Oceania and the Commonwealth of Independent States region.