6 | Tiny Tower
Tiny Tower is the textbook definition of "time sink" -- spending a few seconds with this game can easily turn into a few minutes. As the landlord of a bustling urban skyscraper, it's your task to manage "Bitizens," shops, and job distribution as you try to earn enough money to increase the size of your tower. Part of the incentive is finding all the different types of shops in the game, and matching each Bitizen to their dream job -- by doing that, sales increase, more money rolls in, and you can build more floors in your Tiny Tower.
Be warned: Once you get past 15 floors, you could be checking your iPhone every minute to stock your Pub/Cyber Cafe/Coffee Shop/Laundromat/Night Club or move in a new Bitizen. For a free game, the features are quite robust, yet simple. Of course, if you want to speed things along, you can always buy virtual "Tower Bucks."
5 | Game Dev Story
There are simulation games for nearly everything, whether you want to fly a plane, build a city, or command the growth of an ant colony, but Game Dev Story just might be the first ever game developer simulator. As the new guy (or gal) in charge of a promising new studio, you'll be charged with making the big decisions that go on behind the scenes in game development like hiring and firing designers, coming up with game ideas, managing a budget, and dealing with fans. For us, one of the weirdest feelings was getting enraged at gaming journalists for giving our early games low scores of 3s and 4s -- talk about hitting close to home.
Even if simulation games aren't normally your thing, give Game Dev Story a chance. Kairosoft's entire formula of addictive "slice of life sims" started here, and it's a good jumping-in point. It'll probably eat away your entire weekend before you know it.
4 | Dead Space
One thing that Electronic Arts has done very well with the Dead Space franchise is porting the experience to systems with vastly different control schemes. On the iPhone, swiping and tapping gestures are the core gameplay element used to battle hordes of deadly Necromorphs, and they work incredibly well. Even the production values outclass many other iPhone games with 3D engines, as Dead Space retains the ominous lighting, speedy enemies, and eerie sound effects that made the original game such a frightening title.
If you're really a survivalist, you can also try the iOS version's "Nightmare" difficulty, which basically takes away your ability to recover health during levels. If you need practice, Dead Space's content also includes some neat extras like exclusive weapons and survival modes. Just make sure you have an iPhone 3GS or better to access everything the game can offer.