I love the concept, but after you've done a 100 or so, they're all too easy. But still fun.
I had some trouble with Color Fence in terms of the colors. The orange & red squares are too similar.
Even worse: I wasn't able to figure out which colors should be inside and which outside. Look at image #1. In the top right corner are 3 colors. Are they supposed to all be in or all out? I've tried it both ways and neither worked consistently. I think they've debugged this now.