As awesome as all of your games! I feel I might actually be able to offer advice for once, so please forgive my intrusion. I noticed that the game lagged a bit on the 15x15 puzzles, and, since you're using ren'py (and by extension, python) I have a few tips. What might be causing the lag is that you're drawing every single square to the screen, instead of say, using the grid as a background, or using an image library. If you are already, it might be because you're looping through every single cell and running checks on them all every frame. Maybe try limiting the scope? I'd give more advice, but I don't know if you're using a 1d or 2d array.
Anyway, the game is [bleep]ing awesome, as are all your games, and I loved it. I will go back to enjoying your content from the shadows now.