They've delayed new floors on ToT for years now and yet their patreon only grows bigger (beats me *shrugh*), so I doubt that's the issue here. Also finishing ToT could (in a perfect universe without delays) take a very long time, since the story we know so far is quite little and the potential it has is a lot. Imagine 20 floors all with their sub quests... yeah, they could work a lot on ToT and keep it growing for years and years. My guess is that they lost interest on it as a project as it's not bringing anything new to them.
On the Heelfall subject, if you like these RPG games, this one is very nice. Got a few bugs here and there (one that was game breaking, was the Inn fight, if you lose your battles and are left with only one character, the lady there keeps you charmed forever, unable to act, unable to die, just an endless loop of heart attack, skip turn, skip turn, heart attack, skip turn skip turn, etc, have to alt+f4 the thing to end it). And could use some work on the side missions (being able to repeat a mission where you recruit one guy that is already on your party and overleveled for that mission yet you can't use him, feels a bit odd), but these are minor details of course. This is a side project so for a side project, it's great.