Decent so far. The art style is different but good, the story is interesting, the characters are caricatures but still interesting. No real animation but also no issues with the writing. A good start
History/writing: real good history, good narrative and immersion. Good writing, very few typos or grammatical mistakes. Also not big text walls, the amount of text feels about right and the action pace is correct. Character personalities are well depicted and are unique, they don't feel "plain" or "generic".
Art: Very nice and pleasant. Characters have realistic body proportions and are attractive, also the finished backgrounds are very good. As I mentioned, this is a demo and very few backgrounds are not final (they are generic assets) but most of the art is unique and the style fits very well overall.
Animations: at the moment only use two frames, but again, this is a demo and I'm sure it can be revisited. There's lots of opportunity to improve in this space.
Gameplay: The story feels linear, there are few choices, which usually leads to see one or another scene. It will really depend on the game designer/developer to see if they want to follow the linear approach or create an "open world" where the MC can roam around and progress. But again, this is a demo, so probably as an introduction to the story, characters and settings, a linear approach is the best choice.
Music/SFX: Good sound effects, but I encourage to improve the musical aspect, choose more background music to fit the different events and atmosphere. Use an action driven background music when fighting zombies, use a sexy tune as a background for H scenes, etc.
Room for improvement: there's plenty, but again this is a demo. And a very good one. Very few bugs/typos (which I already reported). I would enable the generic menu options of RenPy (especially "Preferences" as players might want to mute or modify the sound volume), and would add a Gallery option to revisit memories (unlocked H scenes). This is basic in any adult game.
I really liked the demo, I see lots of potential, therefore giving the 5 stars as it pleasantly surprised me for a v0.1 (demo) release.