This was really fun! I love the art style, its clean and consistent, and all the important things jump out at you.
The gameplay is excellent, trying out the different rune combinations is really satisfying. There's so much potential for different powers and items, cant wait to see what you add next!
Level generation is great, no two levels feel similar. The layout always allows for an escape route, I never felt too boxed in, unless I ended up in that position by mistake!
All it's missing is sound, though that could be a problem on my end!
One or two things I noticed:
-When you pick up something that increases your health, it looks like you take damage because your "remaining health" bar gets shorter compared to the max health. Decreasing your max health makes it look like you gained it. It's only cosmetic but it could lead to a bit of confusion.
-Item drops are occasionally obscured behind the top of the walls.
-Ranged enemies often try to shoot through solid walls.
Other than that its a really solid game, keep it up! :D