I'm not much of a game player, but I downloaded Trainyard
which I thought my Grandson would enjoy playing. He did. When the puzzles got harder he started asking for my help.
It wasn't too long before I was playing the game almost full time. I've found this game to be as addictive as Angry Birds. The object of the game is to get each colored train to the correct station by drawing track for it to follow. As the game progresses, you have to move more trains with more complicated track layouts.
There is also a free version, Trainyard Express
. According to the developer, the only difference is the amount of puzzles to solve.