Trains aren't symmetrical. Neither is nature.
That doesn't mean you can't make a game about making trains and nature symmetrical.
Which is good, because that's just what German studio Black Pants Studio has done.
Symmetrain is a fast-paced chugging puzzler in which you tap on the screen to make sure both sides match. Miss a match, though, and your train slows down.
Once your train has slipped off the screen, it's Game Over and your journey of scenery installing comes to an abrupt end.
It sounds a bit weird, but it's presented in a uniquely quaint way. Oh, and matching things isn't as simple as you might think.
Symmetrain is out on iPad and iPhone right now, and it'll set you back 69p / 99c.