Played through the demo and here are some observations.
First is that there is no tension going back to unexplored rooms after defeating each floor boss room. I feel there should be some decision of either moving down the stairs or risking more exploration for more reward. Something like ennemies get stronger if you don't go down the stairs fast enough, or the rooms get filled with poison and you take a damage. Only examples to illustrate the feeling, not necessarily advocating for these specific solutions.
Second, every attack and spawn are telegraphed with red circles and rectangles but not the projectiles like the red slime and dragons fireball. That felt awkward because you are trained to avoid red indicators but the fireball are identical to your projectiles and don't have collision indicators. I feel you should either expect all attacks to have collider indicators or none.
Bonus, the yell sound effect when you get hit doesn't sound good, it feels out of place.
Overall, it felt like ArcHero meets binding of Isaac. Even in this early alpha prototype stage it's clear it will be a buy for me.