Since this is one of my favorite types of game, I enjoyed playing the demo. But. The very neutral palette (soft grays, taupes) made it a little annoying to play. I don't prefer peering at my screen in order to read the numbers and play the puzzle. A little contrast would make it much more enjoyable!
I played the demo in half an hour, and was completely absorbed in the game, the plot and the puzzles. I'll have to buy it to find out how it turns out!
First there were games with one color; then three colors. Now, add shapes! Up to three colors and three shapes creates a complexity that is, simply, hard! I've only played for 19 minutes, and I bought the game. It's hard and it's really fun!