Interesting concept. The art is good, the music and audio decent. My feedback would be the controls. Pressing Left Arrow after completing a round feels counter-intuitive. Like I'm going to undo my selection. I think Enter would be a better option. Also the first couple levels I got the blue card a lot. Level 1: blue, green; Level 2: blue, blue; Level 3: Blue blue green; Level 4: blue, blue, blue, green blue, but maybe that's on purpose.