"What exactly did Subsistence do right? Well, to start off, it included an improved camera and an online multiplayer mode. These two additions, coupled with the updated versions of Metal Gear and Metal Gear Solid 2, helped push Subsistence over the edge with longevity.
The addition of online gaming finally gave Metal Gear fans the ability to square off against their friends in capture-the-flag and deathmatch variations. The Metal Gear community responded positively and it was huge success for Kojima to introduce multiplayer to the previously single-player only franchise."