Neat!
It was quite confusing at start. The instruction didn't do a too good of a job to explain the whole grid/timeline thing. It even took me longer than I'd like to admit to actually find the togglable grid even. And it took me much longer than that to then realize how the toggles worked and thy the left most one kept resetting the puzzle. After finally understanding how it worked, the rest of the levels were a breeze. I think the issue here was that you could easily pass the timeline tutorial level without actually understanding the mechanic. At least if you do it like me and just read the first part and immediately turn every cell on the grid on...
Biggest issues with the game were with the controls and UI. Like I already mentioned, the grid position was just not great. There shouldn't be a need for separate buttons to turn cells on and off, left click for both would work just fine. Quite often it also felt awkward that even after a reset, the level started automatically again. Also, now looking at the above screenshot, wasn't the pause button (and hotkey) completely unnecessary? Didn't start (at least space did) act as an on/off toggle?
Which boils down to the second issue (at least for me). I found that allowing to start the puzzle and then slowly go through it toggling everything on/off as needed took some pleasure from the success. Requiring proper planning and executing, then to see your plan get acted on would be much more rewarding. Of course it would make it a lot harder too so might be just me.
The game looked and sounded quite nice. Obviously nothing too spectacular but clean and clear, and some nice color selections too (no horrible pure primaries like seen so often with simple geometry based graphics). Same goes for sounds and music, they got the job done and didn't get annoying.
The amount of content was quite nice but I kinda left off wanting more. I didn't have time to get to any complex stuff. Pretty much just introduced mechanic after mechanic and then called it a day. Some more complex levels combining different mechanics like the last one would have been nice. And more freeform levels too, the current ones all pretty much had an obvious single cookie cutter solution.
Good job! 👍