I don't know if anyone has noticed but physics based games are always a hit on mobile device. They can be implemented easily into little games which become addictive and highly popular, the people behind Angry Birds can confirm this. Angry Birds is the most popular mobile game on the Android market and iOS appstore.
Cut The Rope
Cut the Rope is a game all about feeding the little frog type thing with candy. But it's never as simple as that is it? The candy is always put in an awkward position so you have to work out your own moves on getting that bit of candy in the frogs mouth.
This was the first game I ever played on the iPhone before I got an Android device. I remember thinking to myself "OMG this is so freakin' awesome", playing it for hours on end trying to beat my mates highscore. The idea is to curl the paper ball into the bin and see how many you could get in a row. Simple but very addictive.
aTilt 3D Labyrinth Free
Labyrinth has been around even before the Android and iOS days, I remember people playing it on their Nokia N devices. The game has been charged up a lot since. The idea of the game was to get a ball through a maze into the jackpot hole. On your way there are obstacles and death traps which get in your way.
A game which requires attention to detail and an understanding of mechanics. The goal is to build the strongest bridge you can with the parts available. Once you think it is ready you then test it by letting a train go over it.
Now we couldn't miss out Angry Birds could we. The most popular game on the Android market. The game produces $1 million a month for Rovio, the people behind it, a month from Android alone. Now that is saying something. If you haven't tried out their Seasons and RIO versions I highly recommend you do.