Activision’s Call of Duty Online has officially entered open beta testing in China.

The free-to-play, first-person shooter has been in development for over three years. Activision partnered up with Chinese Net company and games publisher Tencent to bring their Call of Duty franchise to China’s large base of online gamers.

The Chinese market represents an important opportunity for Activision to expand their billion dollar franchise. Wedbush Securities analyst Michael Pachter put the scope of the opportunity into persepective, saying “700 million [individuals] play games on Tencent’s QQ network,”  according to USA Today.

During a closed beta test taking place from July to September of 2014, 1.5 million unique players were involved.

“We have been going through this very intense testing of the game under larger and larger audiences of consumers,” said Activision Publishing CEO Eric Hirshberg to USA Today. ” We wanted to make sure it was sticky and compelling … and it was a fun, easy experience for anyone to pick up and play and have a good time with.”

Call of Duty Online features single-player missions and both competitive and cooperative multiplayer modes. The game also includes a unique version of the zombie mode found in past Call of Duty games featuring cyborgs. While typically viewed as a console game in the west, this newest game is built for the PC to take advantage of the largest player base.

The game can be played for free, but optional items and upgrades are available for purchase.

“It’s modeled after all the best-performing games, both in that marketplace and worldwide,” said Hirshberg. “Everything from weapons to characters to cosmetic items,which are designed for personalization and expression, to attachements are purchasable and earn-able as well.”

China previously banned all consoles in 2000, citing potential harm to children’s development. However, since this ban was lifted in 2013, both Microsoft and Sony have announced plans to bring their consoles to the Chinese markets. Sony said last week that they would be delaying their planned Jan. 11 release date to continue negotiations.