Standard matching game, some absurd difficulty, and no real fan-service. There are better cock teases out there.
If you know how to do stereographs. do that and the differences will be easy to find
For the 4th girl, click on both paintings. Once you know that, it's a fun game.
I game is interesting, but it gets annoying having the women randomly floating around the page in my line of site when I'm looking for very small differences.
I beat the game, but there are often more differences in the game that aren't recognized. Also there is some kind of bug that prevents me from playing the game again after I had beat it (The last character was brought forward and I could navigate off the page, but I couldn't click on anything. Also the advertisement wouldn't go away. I tried refreshing it and it will only let me click on one girl and even though, it won't let me play the game.
Beat it after about an hour. A couple of them were quite frustrating but I managed to hang in there. Not too bad, but not great either.