What a wonderful little puzzle of luck! The atmosphere is immaculate, and the mechanics click together nicely. I was thoroughly engaged!
I think it could've done with a couple of smaller board choices, to help ease players into the logic of filling the board correctly. A couple of outright tips might also be warranted (like the fact that colors can never exist in a 2x2 square, or that directing dashes and solids into the same square is an instant lockout).
Fantastic! Great work!
[EDIT 2025-10-06]: Struck out incorrect information. Colors can exist in squares and rectangles if all tiles connect to each other with lines.