I can summarize the gameplay in two main mechanics, collecting blood and upgrading a tree. That's what you'll be doing for like an hour of demo to complete it. And unfortunately I have to say they're not really well polished, at least not the blood collecting mechanic.

The mouse doesn't have an indicator for the radius, so I know I upgraded the mouse radius, but I just don't know the limits that upgrade and it's the most important (the only?) mechanic of the game, collecting blood. I want to see a border to clearly see where I can extend myself to catch the blood. Otherwise I'm blindly hovering the mouse hoping to get it right.

Also the "magnet" to catch blood is too finicky, if you move too fast it won't catch them, you have to move slowly to make sure you get them all.

The collectors, I don't know why they have a square area, it feels like an odd design choice (both mechanically and aesthetically) since the whole game is circles.

The camera wobble is so annoying, I didn't know I could disable it until I later when explored the options, I don't know what it adds to the game really, it makes a finicky gameplay even more finicky because now you have to compensate for the camera movement to aim at the red pixels, I would remove the wobble completely but that's just me.

For the points mentioned above, the game never felt super satisfying. It felt "ok", but I never felt like "Look, it's so AWESOME I'm collecting all this blood" because it always felt like I was missing something, either moving too fast so I was missing blood, or some blood got uncollected which left me unsatisfied all the time.

The prestige is a bit confusing because there are prestiges and semi prestiges, and the heart helps with the prestige but it's not the prestige itself... a bit convoluted until you figure it out, also I really don't see the point of the semi-prestige mechanic, just adding a high blood cost to the upgrade might seem enough (I know blood rate is not the same as blood amount, but I'd say it's not worth adding a new mechanic just to justify the cost of ONE upgrade).

The angels... I can't tell if the add anything of value to the game, it's just another circles with a different "follower skin", different blood color, sifferent way to sacrifice them and a secondary tree. It's "more of the same". I'd probably rework them to be something different (like a multiplier for blood, or something like that) or I'd remove them from the game to add a new, fresh and different mechanic. I know it's probably late for that, but that's my feedback on the angels.

It's not idle, it's a highly active incremental, I don't know why it's tagged "idle".

The game has one main mechanic, to collect blood, and the fact that its only mechanic is not polished is a bit of a negative point for me, but I'd still recommend it, it's a good demo to play for an hour or so.

Hope it helps!