As already mentioned, it is a prototype and not a demo. It only shows features and a small insight.
Viewing post in Succubus Dungeon (NSFW 18+)(Patreon Version) comments
2 things
1. i didint see any mention of this game being a prototype on this page it really seems like a full release/beta
2.id also like to mention that black on grey on grey is a horrible choice for a page design as their all colors that slowly merge together id maybe suggest on changing text color or even background color to make things easier to see