Yup, you can't move to them. Weirdly I didn't notice them at all until several attempts in (and was getting confused as to why certain moves weren't allowed), in a way that reminded me of the Selective Attention Test[0]. Once I'd clocked them I was able to solve it pretty quickly.

[0] https://www.youtube.com/watch?v=vJG698U2Mvo

That Selective Attention experiment always amazes me. It's like one of those things that shouldn't really work but they somehow do. Like welding an impossible triangle.

Also, on Firefox for android, you can't move pieces downward. The browser hijacks the "drag down" gesture and refreshes the page.

Workaround: pick the piece and move the finger upwards, then you can freely move it around (as in, instead of press-down-release, do press-up-down-release).

The pull to refresh has been very broken since forever. Apparently they enabled it by default in the latest version because it was "very stable" but I'm not so sure...

sorry to hear about that! do you mind sharing which device and version of android you're on? I believe what anilakar said is correct

The drag down gesture in Firefox was disabled last year because it interfered with page content. Are you running an old version or did you explicitly re-enable that behavior somehow?

It was re-enable by default last week, in version 124.

Interesting. I'm running the developer edition everywhere and they didn't apparently consider it necessary to re-enable it there :-)

Drag selection is problematic on mobile devices. Click and select is the way to go.

Correct. Apologies for not making that clearer! in some puzzles it is much more obvious than today's because the obstacles connect to create long connected walls: https://echochess.com/game.html?game_mode=DAILY&level_type=E...

Maybe make them look like rocks or brick walls?

Yeah I think that might actually be a good idea to try out. I tested a few things with shapes during the beta but they kept looking too '3D'ish for the rest of the theme. Not sure if I'm explaining it right but the obstacle shapes kept popping out of the background somehow. Do you know what I mean?

A more minimalist approach might be a small "x" in the center of each square.

That's a good point. Experimented with a few "big" X's before and it just wasn't doing it. The small x in the center might actually be it.

Nah, try the universal "don't go here" indicator of close diagonal lines like you see in parking lots. Keep the shading of the lines and the square background relatively similar so they convey the message without distracting from the rest of the board.

That's a great idea too. Thanks guys, please keep the suggestions coming if you have other thoughts.