Hopoo Games has revealed that it has begun work on Risk Of Rain 2, and this sequel will be a 3D game, moving on from the 2D view of the original. Hopoo has stressed that development is still in the early stages, so there is no release window and the final assets, designs and systems could be different from what has been worked on at the moment.
There are a couple of gifs that show the direction Hopoo is hoping to take Risk Of Rain 2 in.
Hopoo will be writing regular development blogs to update on the progress of Risk of Rain 2. No platforms have yet been confirmed.
Source: Hopoo Games