Thanks! Yeah, I like how the green palette looks, I did it before in ( https://snakewinter.itch.io/lost-in-a-place-that-doesnt-exist ) and the only problem I have with limited palettes is stuff blending together/running out of shades to differentiate. I think using gradients helped in this one, but another problem I noticed was it looked easy differentiable on one monitor, but then on another, stuff blended in more making it harder to make out.
I'm not sure about shaders. About the gameplay, I kind of regret not having more enemies in it, but the one in it was the last new thing I added to the game.
There's only one tiny secret area in the game. After you get through the second keycard door, you can turn around and there's a tiny dark wall to shoot down, then a sign at the end of that hallway. And this isn't a secret area, but I also had some fun jumping from the bed to the top of the walls, then walking atop the whole level and jumping down to the final section from there.