Just a note to generally answer all the latest comments, and those still following this thread and hoping for a comeback. The dev abandoning the game "due to unity" is most likely just an excuse, or at least not the only factor.
Unity's runtime fees (which were dropped a month later, the recent news 1 year later are related to Unity 6) affected only really big devs and companies (those making 1mil a year), moderately big devs (those making 200k a year) only had to pay 1500 dollars to upgrade to Unity Pro and be totally fine (which is still required anyway if you're making that much yearly).
Not saying it was impossible for him to reach that much, he is/was clearly quite talented, but there were (and currently are) much bigger Unity games which have never abandoned and were nowhere close to hit the runtime fees still.
I won't answer to "but unity is still bad" replies (if any) as I do not want to go off-topic on this thread, but just wanted to say it's very unlikely that the dev will resume this project only because Unity 6 also dropped the runtime fees.