Great, responsive dev on the forums who updates the game regularly. That alone made me willing to purchase it at full price.

I am starved for good Online Co-op games that are Linux native.
And this is a good one.
As others have said before, the skill tree looks like Path of Exile (in a good way), and so far (7½ hours at time of writing) it makes it so that there is room for improvement of gear, or trying different playstyles, and it makes it rewarding to get gear with better rolls; it's not a mindless grind, the mechanic really feels comfy.
I wonder how much more gameplay diversity there is, because so far, aside from some light dodging, there hasn't been much of a "mechanic" to any boss or such.

Anyway, I conclude that the game is worth its money.
Or it would be.
There is one thing that really really bothers me.

Początkowo opublikowane przez author in game description:

Most in-game sprites and item art in this game were generated using DALL·E. As a solo developer, generative AI tools allow me to create a breadth of visual content that would otherwise not have been possible.

Then pay an artist. The same way that someone might hire you – a programmer – to write code, if you need art, then go out and hire an artist. You wouldn't want to get fired and replaced without pay or compensation because "AI" produced sub-par code cheaper than you, so why are you okay with not paying the literal profession which does art?
And yes, the "art" in the game is sub-par. It is clearly generated. From the general artstyle for slightly photorealistic art that neural networks output these days, to the broken yet very distinctly visible geometry of the dice in game. It just looks bad[xkcd.com] if you look a tad closer. The game is fun in and off itself, but the lack of artistic identity just makes it blend into the nothingness of my overly huge game library. Case in point I couldn't even tell you the name of the game off the top of my head right now.
When you see Borderlands' cell shading and even the artstyle and character design you recognize it.
When you see Elite Dangerous' HUD you recognize it (if you've played it obv.).
There is a style to either of those that makes it stick out, makes it unique.
This game does not have any artistic identity at all, and it manifests by literally making me forget its name three seconds after I've seen it in my library.

Just please go and pay an artist to conjure up (art is magic to me) a general style for the HUD so that it looks somewhat distinct stylistically, and pay an artist (potentially a different one because every person has a slightly different set of skills) to draw up a cohesive set of characters. And which ever you get done second, hand them the work of the first so that they can make sure the styles match.

If your response to all this is "but money" then my response will be "fine, then instead of buying your games I'll feed your store page into the next neural network and make it write the game for me for free" because if you think it's fine to not pay a professional (an artist) for your game, then I should be fine not paying a professional (you) for this game.