RGB Express, by Bad Crane, is a mini-truck puzzle that packs a lot of game onto it's tiny highway. It's cute, challenging, and has recently been updated.
Now players with an iPhone 6 and iPhone 6 Plus get to enjoy some enhanced graphics, and everyone will celebrate 40 new levels to ponder. Bad Crane has also added Japanese language support smushed some bugs.
You can get RGB Express in the App Store for $2.99.