Novel solutions:
* F12: https://imgur.com/a/gtKGbnT
* H10: https://imgur.com/a/EfwnxRZ
I enjoyed the game a lot! Reminds me of some puzzles from Cracking the Cryptic (snakes, lights, galaxies). This game is kind of in the middle between CtC and The Witness for me. CtC is all about making a sequence of logically sound deductions, aided by the UI that lets you place various markers on the board; Witness is more just yoloing some guesses and getting a feel for what is likely to work, because you can only hold so many deductions in your head without resorting to pen and paper. Gridspech is a bit of both.
Minor UI feedback:
* For the three-color puzzles I wish there was a way to label a cell as uncertain between two colors, i.e. "not green", "not purple", or "not blank". No idea how to make a good UI for it though. (Middle click to toggle between e.g. "green" and "not green"? Sounds cumbersome, and doesn't generalize to more colors. Something like Cracking the Cryptic's keyboard controls for colors? Ugh.)
* Undo. I wanted it for bifurcations occasionally, but not too badly.
* Sometimes it's mildly annoying that you can't interact with the grid for ~2 seconds after submitting an incorrect solution. I wish clicking the grid would interrupt the animation, or maybe allow toggling the cells during the animation (but then it might be a little confusing if the symbols keep flashing based on the previous state of the board, not the currently shown state). Useful when "submitting" just to see which symbols flash, either for experiments when exploring a new mechanic or for sanity-checks on a partial solution.
* Clicking in the narrow empty space between cells toggles the cell below or to the right, rather than the closest cell.