Online social gaming startup Raptr has partnered up with NHN USA. While the name NHN may not ring a bell with most gamers, the site it developed, ijji.com, may.

ijji features popular games such as GunBound Revolution and Lunia: Record of Lunia War.

Under the agreement, various ijji games will include the Raptr client. The first title to sport it will be GunBound Revolution, followed by Drift City, GunZ: The Duel, and Soldier Front.

The Raptr client itself is like a mix of Facebook and Twitter, but geared towards gamers. Users can not only add and message friends, like any other social network, but can also see what their friends are playing and what achievements or trophies they’ve unlocked.

And by actually integrating some of its functions with Facebook and Twitter, Raptr is expanding outside of traditional “hardcore” gamer circles.

Granted, it also appeals to these crowds as well. Anybody who cares about what achievements they’ve unlocked is generally considered a hardcore gamer, obsessive-compulsive, or a liberal mix of the two.

Either way, Raptr’s client looks to be an excellent way to keep in touch with gamer friends, especially considering that gamers don’t necessarily use (or want to use) headsets or keyboards when playing and that everybody uses the Internet.