Currently the tool is under development and will not be expecting any repository updates until Undertale Purple, which utilizes this tool is finished. This project is only made open-source for viewing ...

Undertale Together is a mod which allows the game to be played in couch co-op, but players have several ways of using the mod to play online co-op.

It’s no secret that Undertale has slowly built a ravenous, cult-like following since its release last September. One intrepid fan has created a 3D mod for the game (via Siliconera).