I was thinking a bit more about their upcoming collaboration with Professor DM to expand the game to level 20. While I certainly have not played every single TTRPG ever and my experiences are only my own, I struggle to think of a D&D adjacent game where the gameplay experience is improved by reaching the higher experience levels.
Most of the time the decline in my enjoyment of the game starts around level 9 or so for a variety of reasons, whether it simply be my interest in the current characters having run its course or mechanical issues with the system being exposed. I think that's one of the strong appeals of Shadowdark to me, since the cap is level 10. I haven't experienced level 10 gameplay, but even just looking over the tier 5 spells and the more powerful magic items gives me a lot of confidence that the gameplay loop should hold up to that point.
Perhaps they can manage to thread the needle and come up with something that keeps Shadowdark fun and engaging all the way to 20, but IME history isn't on their side. That could just be a me thing though, either way it will be interesting to see what they come up with.