GGPO (http://ggpo.net/ http://ggpo.net/) isn't exactly drop in, but it works well for most games that require low latency and have minimal per frame state chang

GGPO (http://ggpo.net/ http://ggpo.net/) isn't exactly drop in, but it works well for most games that require low latency and have minimal per frame state changes (most arcade games). Integrating a GGPO like solution into Game Maker or Unity might make it easy to enable netplay for most games in the style of modern local multiplayer indie games (Bari Bari Ball, Hokra, Samurai Gunn, Towerfall, Nidhogg, etc.) Unity announced a complete rewrite\update of their existing network code (http://blogs.unity3d.com/2014/05/12/announcing-unet-new-unity-multiplayer-technology/ http://blogs.unity3d.com/2014/05/12/announcing-unet-new-unit...), but it seems to be mostly be a fixed implementation of existing functionality rather than a true drag and drop networking solution. In practice there is no solution that works for everything, but it should be possible to build a solution that works reasonably well for a large subset of games.