I enjoyed the way it gets tough, but when they want to teach you a knew mechanic, like two colors, they don't spend 2 minutes describing it to you, they just gave you a couple of easier levels to allow us to figure it out, good concept of hard then a little easier to teach
 "Strand"){kind=icon}
 "Magic and Empire"){kind=icon}
 "Vortex Point 2"){kind=icon}
 "Realm of the Mad God"){kind=icon}
 "Card Monsters"){kind=icon}