At first, it was very unclear what I was supposed to do. I find it strange that you have two signs but neither of them says what the line is actually for. The blocks don't stand out as being important, so I kept trying to make the line interact with the circles instead.
The menu controls don't work properly. Half the displayed keys don't do anything at all, and resetting never worked. I quit and re-opened the game, thinking that would reset the blocks, but it didn't.
I have both blocks stuck against a wall (vertically at the bottom of the map). When I tried to make a line through them, it got buggy and made an endlessly repeating sound until I made a new line segment. They never moved from that position, but I was still getting used to the controls and probably missed something.
Upon re-extracting the game files, I tried again and had a much better time. The first two rooms were good. The third room was pretty cool. I really like this gameplay mechanic.
My only complaint about the mechanics is that I found it irritating to have to use different controls to change which direction I was facing. I would've preferred for a short tap of the button to make me face a direction, while holding it would make me move.
I wasn't sure why the choice was made to make movement so jerky. Why not let it be smooth but stick the player to the grid when they stop moving? There's so much backtracking and I found it a pain to walk like that all the way back and forth.
Some of the sound popped and crackled. It usually happened when I walked over a special ground tile.
I actually kind of liked the graphics for the character and the ground. Interesting color palette. The green doesn't quite fit with the rest, though.
The music seemed fitting and grew on me.
I really like the concept and the puzzles were pretty good. I especially like the ones where you have to pull the blocks the opposite direction from where you're facing. It just felt good for some reason. Anyway, I stopped playing at the blue maze (one room right from the key door) but I may go back and play more.
Re: menu controls, I tried to make the distinction between "buttons" (for controllers) and "keys" (for keyboards), but I realize I didn't 100% do this, so the game has been updated in the original post to accommodate. I also fixed the problem you were having with resets. I had the endlessly repeating sound bug a long time ago, but thought I had fixed it. If you or anyone else comes across it, let me know!
As for some of the other ambiguities you mentioned, I wanted the game to have a sense of discovery to it, thus not everything is spelled out. I think it feels more rewarding in that sense, but I'm willing to be proved wrong in that regard.
Regardless, I appreciate your feedback, and I'm glad you're enjoying it so far!