There was a this spate of hyper-productivity about a year ago where he cranked out all the hybrids in less than two months. I mention this because it is proof that he can bust ass when he wants to. Even before that the game went through a lot of changes, new areas being added, the critters stopped spawning out of the ground, leashes were removed, surprise sex became a thing, and lots more. Then things slowed down a bit but stuff was still happening: We did get two new positions since then (lotus and waterfall), and some size expansions with existing ones (once upon a time your human breeder literally had no sex scenes outside his own Medium size), and the shark girls, bee girls, elves, orcs, starfallen and goblins got added... even if they all suffer from a bad case of same-face. The map got remade more times than I can remember, too.
It was pretty damn impressive.
And then... I don't know what happened. The "breeding task board" got added, which is something I see actually being useful in another, oh, five or six years of development. Right now, though, most people don't even know it's there and those that do couldn't care less about it. Then the mermaid got added, which gave players hopes of there being a new mermaid to capture, but nope, it was just her and she was originally just there to remove the grungy trait that nobody asked for in the first place. Then he added death-by-falling, which I admit is realistic but again was something that nobody had asked for. And the latest farce is the so-called "quest system" that, once again, nobody asked for.
Now I understand the need to put something in the game other than just more sex scenes. Hell, I was one of those people asking for that myself. However, things that people wanted like actual gene mixing for colors (instead of coin-flip premade paint schemes), the potion system promised years ago, and more breeder customization options that everyone was asking for have all been ignored. Stats still mean nothing and there are still zero interactions besides sex and milking.
Meanwhile, all development seems to be focused on end game stuff. Does there eventually need to be some quests? Sure! Do we eventually want that breeder request board to mean something? Sure! But these are things that should have been added way down the road and after more important (and more desired) things were done first.
Half the sex position chart is still full of Xs. There are no potions, no equipment, no items other than fluids and even those only exist for captures and selling. There is still only one breeder outfit. Stats and levels are still meaningless. There's still no farm upgrades other than the critter houses. Fast travel is still a chore (why the fuck is the farm portal on the opposite side of the farm from your house?) and exploration even more of a chore (yes, it looks great, but even the most impressive backgrounds are still just backgrounds). You're face choices are anime-sameface and ferals, and feral faces can't even be adjusted at all (try it - the sliders do nothing) - which is especially bizarre considering the sheer number of sliders and randomization options for everything below the neck. And we still only have, what is it, four hairstyles for every critter in the game?
In summary: It's not that DH isn't working. He's still moving ahead almost as fast as he used to. The problem is that it seems to be entirely in the wrong direction.