Terraria: Otherworld was announced way back in 2015 and it appears that not much progress has been made since then. The owner of Terraria, Re-Logic, has announced in a form post that the Terraria spin-off has been taken from Engine Software and handed to a new dev team at Pipeworks.
Engine Software were contractors for the project, but it appears they've not necessarily done a satisfactory job.
Re-Logic said in the forum post: 'As much as we hate to say it (and in spite of all of the reforms we tried last year) - the current state of the game is still equal parts far from that vision and well behind schedule.
As a result, we have made the decision to move on from having Engine Software continue development of Terraria: Otherworld. Re-Logic has possession of the game (code, art, sounds, etc.) as it exists today, and we have been examining the array of options available to us to get TOW to a place to where we can confidently deliver on the vision and expectations we all have for this game. After taking a good hard look at everything, we feel that a new and fresh start/direction is the only way Otherworld will ever reach its full potential at this point'
Re-Core went on, 'Come whatever may, quality is simply not something we are willing to compromise on to make a quick buck. It may be painful in the short term, but our sincere hope is that it will pay off for everyone in the long term. Clearly, had we known this would be the scenario way back then, we would have held off on announcing the game until a later time - but such is game development. That said, we are really happy and confident with the new team and new plan - and cannot wait to get back on track.'
The new developer, Pipeworks, has experience with Terraria, having worked on the re-write on mobile and console.
Re-Core's radio silence on the matter is very understandable. Fans on the forums seem pleased the project is moving again. Hopefully future updates on the project can now come at a rate higher than the previous average of one per year.