parasaneのコメント

SPOILER about waiting-out the entire hour: the game does acknowledge that time is up, but permits you to continue.

I can verify straight up through 142 (latest as of this writing) is solvable without guessing. However, like the user who reported being kicked back to the menu after finishing 122, I found the same to be true from 141 now. Further - whether coincidental or not - it also turned the grid view on. This is on the latest Ubuntu/Chrome combos. Other than that, my only issues were in frustration with the puzzle rotation when I would make a guess (and was wrong). I had wished that there was a way to disable that, but it would've made the degree of difficulty significantly less, which would feel more like cheating, since you could more easily brute-force all of the levels.