Fairway Solitaire is a free game on iOS - it's a solitaire game with a golf theme which lets you pay £1.69 to unlock about a billion levels, and also has a bunch of other in-app-purchases which I have totally ignored.
The idea is thus - you have to get rid of cards to below a par, a certain amount of cards, by selecting cards on the field which are one higher or lower than the one you are holding. You can draw cards from the deck to get a new card, or you can use a golf club to change number, say using a 9 iron to get a 9 card. There are water hazards and sand traps which make certain levels tougher, and there are 3 stars to get depending on how below par you are.
This game gets into your brain. For a number of weeks I just could not stop playing - every opportunity I'd whip out the phone and knock a level out. And I have not even managed to finish all of the levels. It gets really, really hard later on and I tapped out a couple of sets of levels before the end. I totally intend to go back and earn enough points to buy the bonus levels but I have enough iPhone games to play without spending all my bus time on Fairway Solitaire for months on end. 5/5 stars, you should get this if you like solitaire, golf, or have a bunch of free time sitting around waiting to be sucked up.