According to Konami, players will be logging off Metal Gear Online for the last time on June 21st of this year, roughly four years after the game first launched. On March 21st, the in-game shop will be just down in preparation. In April, you will no longer be able to create new characters. However, all of the game's expansion packs will be free until shutdown.

At its largest player base, Metal Gear Online boasted 1.3 million members back in 2009. The PS3-exclusive game was released with copies of Metal Gear Solid 4: Guns of the Patriots. Metal Gear Online has, ever since 2011, been having a rather large problem with cheating in-game, which may have contributed to the decision to shut down.

[Kotaku]