Game Boosting refers to the practice of gamers to pay other, more skilled players to "boost them up" to higher ranks, mainly in competitive multiplayer games. The practice sometimes takes the form of paid partnership with a team of skilled players (where the player that's receiving the boost is of much lower skill, but gets pulled along with the remaining members of the team's efforts) or by actually giving a player access to your account, to play as if he/her was you, and cashing in on his/her better "skillz". This practice, it goes without saying, goes against the competitive nature of certain games, and if you know your South Koreans, you know they take competitive gaming very, very (really, very) seriously.
This is why the country is seemingly looking to put an "illegal" tag on game boosting, as in, illegal enough to warrant prosecution and an actual sentence to jail (a maximum prison sentence of two years and a fine of 20 million won ($18,000). This isn't something that has been cooked up overnight: an amendment to the "Law on Game Business Development" bill was first proposed earlier this summer, and has now passed the National Assembly Legislation Review Committee, bringing it one step closer to becoming law.