Sudden Attack Online is a Free to Play, First-Person Shooter (FPS) MMO Game.
''Sudden Attack is a free to play, online multiplayer first-person shooter. With small, intense maps, a variety of fun modes, and a wide choice of weapons, this is a back to basics FPS. Sudden Attack is a free to play game, like all other Nexon titles. Sudden Attack features a wide range of customization options for your character, convenience items, and more, which can be purchased with Points (in-game money) or NX (Nexon’s website-wide currency).''