Maybe put the instructions you listed here on the site. I tried before reading the comments and got nowhere.
(Edit:I just noticed the instructions on the page bottom… move them up)
For me the symmetric pieces and the ability to just draw on any square on the grid to highlight it (even those that aren’t part of the shape you have to draw) was at first confusing (some Tetris pieces are symmetrical and you can’t flip)
it took some getting used too but it is oddly satisfying.
That’s my feed back. Well done.