Interesting start, indeed!
As other said, the atmosphere/aesthetic is spot on ; tho the map is a bit hard to read at a time (the fact I tend to have pretty low luminosity on my screen may be the reason)
Content wise, I fear it'll quickly become repetitive - especially since how long combat animation last : as good as they, I think they'll quickly overstay their welcome. Having reason to use different skills ; or fight that end quicker could help.
Having to fuck everyone is... A thing, I guess ; but again, with each goon sharing the same skin/animation, it's leaning more on the "chore" side of thing.
(plus fucking dude, and worse every dude that come the MC path is not my kink. Maybe it's not just the kind of game for me, sadly since I am really appealed by the aesthetic). Having option to aviod sex on multiple occasion would be a good point in my book.
And, unless dev have zero appeal to that sort of content, please add some f/f action that are not just draining other succubuses! Women deserve some love too...
In summary: Great aesthetic, a bit too light on content so it may become repetitive, overall a nice demo.
And I'm definitively jelly : that damned succubus stole Isabella's sexy time, give it to us!