I absolutely love puzzle games. They’re my preference when searching for mobile games. This one came highly reviewed, although, I sort of regret purchasing it. It’s better than a 1 star game for sure. The first world is very entertaining and proves this to be a great concept for a game, but by the end of the first world, it becomes brutally difficult. As in not fun. Be seriously prepared to spend an hour or more on a single puzzle. You’ll be staring, guessing, and trying all sorts of solutions to route a train that gets adorable alien riders to their home. Then, when you think it can’t be harder, they throw in stuff like certain aliens have to ride a clean train before the slimy aliens can ride. Ugh. It’s just so tough. No hints either - not that those help because every single level would require hints. Less of a puzzle game and more of an exercise in futility. This coming from an electrical engineer who loves to game and solve problems. I may come back and try harder at a later time. For now, this lands well behind King Rabbit and Slayaway Camp, among other choices for me.