S4 League (Korean: S4리그) is a free to play, third-person shooter genre multiplayer online game developed by Game On Studio and published by Neowiz Games in 2007. It was published in Korea by Neowiz Games, Europe and North America by ProSiebenSat Games, Thailand by AsiaSoft, Taiwan by Nine Buddy Games Inc., Japan by Game On Studio, Indonesia by LYTO Games and Latin America by Yuisy.

The core theme of S4 League is expressed by its title phrase, “Stylish eSper Shooting Sports” (from which the game derives its namesake). Each “S” in “S4″ describes the game’s identity.

Players are divided into teams in which they work together to complete game objectives specific to the gameplay mode. Players and teams use eSper skills, acrobatic stunts, and a variety of equippable weapons to compete for the best score.