An excellent game
I think overall this is a pretty good game. The choices for music fit the game well and the graphics are very colorful, almost as if they we're from a painting. I liked the style of the game.
But to the gameplay. This is a basic difference game with some backstory added to it. It does add a purpose to the game, but it felt as if the plot and the characters were forgotten right after the intro, apart from the text bits after completing a screen.
Difference hunting in itself was quite the challenge. I did manage to beat the game, but I did take a long time on each screen. Some of the differences were subtle, which was okay, but the some of the differences were extremely difficult to see even when holding the cursor on top of a spot and comparing the two windows. While the flickering of the right screen made sense storywise, it made the job even harder. My eyesight is quite good, so I'd say some of the differences were way too small (small change in grass shape, slightly darker/ligher patch of grass within grass etc...) I still liked how the backup rune system didn't just give an easy way out, but challenged to look for the differences.
Overall, the style of the game is top notch. But, finding all the differences with just three backup runes can be extremely, and sometimes even unfairly difficult.