Firstly, I've mentioned before I think but I'm colourblind. The secret glow is hard for me to see against the colour scheme of the level even when knowing it's there. It just kind of blends in for most of the area where the detector blocks are. I checked that wall but completely missed the glow. Now, this could be from colourblindness or maybe I wasn't paying enough attention. I have to admit I played this level simply to beat it (which is not how I normally play KS levels). So I didn't rechecked the wall. Would I have seen it had I checked again? Who knows.
I hadn't considered this possibility. It's hard to avoid that here because of the color scheme of the tileset I'm using, but I'll try to keep this in mind for future releases.
Secondly, I did see the visual clue of the water drop falling through the water. However, I assumed this was simply due to a layering error. I guess that comes from own experience with the editor and how it works. A casual player who doesn't use the editor much might not think that. But I guess that's the real challenge: finding something that is discoverable for both newbie and veteran. Or maybe some secrets should be exclusive to veterans. Who knows.
I'm not a fan of the classic "check every corner for unmarked non-solid walls" approach in KS levels, so I try to get creative with secrets whenever possible. It doesn't work very well sometimes :oops: I actually tried a different kind of visual hint for that secret at first (a slightly translucent white water tile), but it clashed too much with the "shiny" KS+ tint I'm using. When I made the tile barely visible in KS+, it looked way too obvious in regular KS, and when I made it barely visible in regular KS, it was completely invisible in KS+.