Defenders Quest were not only making the second game, they were rebuilding the first one onto a better engine (the same one as for 2, iirc) than whatever it was using previously. Not too surprised they're taking awhile.
That is only partially true. While it is true that they released a DX Edition, they also said that they hired an eternal team for that job and didn't draw any developers of DQ2 away.
So yes, they did make the DX edition but this shouldn't have affected DQ2 in any way.
Also I remembered I backes War for the Overworld. The game did pretty much the same as Yooka-Laylee, they baited players with Nostalgia, just in this game it was for Dungeon Keeper. War for the Overworld is actually a really good game and we even have the ame voice of the advisor as in DK2 but as far as the game comes it wasn't that close to DK as people have imagined.
Plus, when it first came out (and I mean the full version, not the EA version) it had terrible AI and UI problems that didn't belong into a full game.
Since then they constantly released updates to fix this. The biggest issue for me really was the UI. That looked something like the AI War 2 Ui looks right now and that is just a placeholder. You get thrown with a lot of technical stuff if you hover on your units, something a player does not want to look at. They fixed most, if not all problems since then and are still balancing the units because of Multiplayer.
They also released a mini expansion (for backers like me for free) and recently brought out a "sandbox mode" were you can freely design your dungeon to your liking or somethign like that. Haven't played it yet.
Overall, the game itself is good, not exactly what you would have excepted froma remake of Dungeon Keeper but for itself quite good. But the initial launch was a disaster and that happens way too often with Kickstarter games, hell, even with normal Early Access games (with those actually even more).
Mighty No.9 will still haunt many people I believe.