I will have to go for Ketchapp. 90% of the games which they made till now ( around 25-30, if I'm not mistaken ) are very entertaining, and they would occupy your time whilst you travel by bus, car, train etc. Their games are also addictive and you will have the urge of spending money, but I advise you not spend any dime because thereafter you will want to spend a lot, like I did. Games which I recommend you are: Circle, ZigZag and Stick Hero. These are the ones which do the deal for me. What about you? Have you got any favorite developer?