An absolute treat. There's some great things at play here, and the simplicity of the gameplay itself really allows the visual and aural features to shine.
What I think really sticks with me is how I feel like you nailed the pacing. I feel like you landed in a really good spot regarding how and when the game ramps up in difficulty and you start ushering the player into thinking in new dimensions. From simply staying out of cones, to going around tables and behind objects to intentionally putting yourself at risk to kite enemies away from their patrol - it just feels right.
Initially it took me a moment to understand what was going on with the cones visually appearing and moving around my character, but once I understood it was my own line of sight everything fell into it's place. Maybe I just missed this feature in an explanation somewhere, but consider making this feature even clearer, possibly in the first room you start in?
Furthermore, i'm so glad that you decided to not have a system in which the player would eventually run out of lives and be met with a game over. The fact that I could just keep playing and try again immediately when I got caught was a huge reason that I stuck with it for as long as I did and that I was always engaged and having fun. While it might feel tempting to go hardcore and really punish players In a game like this you went the other way - very smart move!
The ability to hide in the barrel I didn't really understand. I feel like I got caught even though I got in it if I was already in an enemies sights, but if I used it prematurely I really just lost my bearings due to not seeing what happened around me, so I never felt like I had a reason to opt for it over just playing smart with my movement. While the idea of an ability besides movement is cool, maybe re-iterate on what you want to accomplish with this?
A-grade pixel art. Audio and music is f*cking smashing, and that's coming from a technical sound designer. Just wish tunes would change as I got to new roomes, but that's just me being greedy.
Congratulations to a fantastic achievement!