This was a project by the original developers, not by gearbox. The original game, while incredible, had stability, optimization, and probably most importantly, multiplayer issues.
The community had asked for a way to play together online without third party solutions, but the code base needed to be rebuilt to facilitate that.
Risk of Rain Returns – Launch Trailer (www.youtube.com) angielski
(This is a remake of the original Risk of Rain, out now)