It's getting really close, though. Puzzles, mechanics, dialogue, effects, all finished. At this point, according to the dev, all that's really left for him to do is "small things like fix collision bugs, and I will keep placing props in levels and program the occasional cool 4D thing. We still need a bunch of 3D modelling done."

I'd give a 50% shot it lands on Steam before the end of 2019. (35% it doesn't make 2019 but lands before the end of 2020, remainder that it lands later or never releases.)