A few days ago I interviewed Dark Curry and I had the chance to try Undead Citadel, here you have the article, in Spanish:
Here you have the last version of the complete first level of Undead Citadel (in English) with the introduction and the tutorial.
You also have this horde mode gameplay.
Since their offices are less than an hour from my home, I think I can lend them my Pimax 8K, if they need to run tests.