geoDefense

 Yay, another iPhone tower defense game! 
 
I was drawn to the price (1$) and the graphics but after playing geoDefense for several weeks, I find it one of the best tower defense games on the iPhone simply because it is implemented so well.  The game doesn't do anything revolutionary or ground breaking so if you're weary on the whole tower defense genre, you can probably pass this one.  But if not, this is one of the best executed TD games on the iPhone.  


The graphics bring the action to life.  The style is very reminiscent of Geometry Wars, with simple shapes and swirls traveling along a pre-defined path, harried by your geometric towers, which themselves fire circles and lines.  But it's really exhilarating and shiny to see your dozens of towers pound on a group of enemies with pixels flying and the screen flashing to epilepsy-inducing proportions till they pop and their pixel-bodies get absorbed into your batteries.  It all comes together really well.


geoDefense towers consist of your standard pea shooter, laser (straight line shooting tower), homing missile (splash damage tower), and slow tower.  Also included is a 'battery' tower that absorbs the remains of your dead enemies and charges other towers linked to it so that their next shot is far more powerful.  The towers are also upgradeable, with changing behaviours like allowing the missile tower's missiles to re-acquire a target if its initial target is destroyed before the missile lands.


All of these seem simple and mundane enough but the difficulty in the later levels really shows you the subtlety of tower placement and upgrading.  For example, there is one creep that deflects particle shots (e.g. the pea shooter's bullets and the missiles) but the max level pea shooter is a sniper gun that can penetrate this enemy's deflector shield.  This makes it one of the best ways to take this enemy out.  Another example are the purples diamonds which are almost impossible to hit in some levels without a slow tower or the yellow squiggles which succumb to concentrated missile fire because of their tight packing.


The best part is that the Hard levels are actually quite challenging.  You'll be able to blow through the easy levels and the medium ones may stump you once or twice but the hard levels will have you cursing your iPhone till you figure out the exact placement and even build/upgrade order that maximizes your chances for survival.  These levels will take patience and trial and error but finally defeating that level after 2 days of on-again off-again attempts is extremely satisfying.  This difficulty forces you to understand the subtleties in each tower, how to optimize their performance, and where you can get the most damage per dollar spent.  It's all very rewarding and extremely fun.  Best of all, each level lasts at most 10-15 minutes, you don't feel like you wasted a lot of time if you die on the last enemy.  The balance is just right and you never really feel cheated that you lost.  Instead you always feel that you'll win if you had just placed the towers a little better or after analyzing your failure, a better strategy emerges to maximize damage. This difficulty is quite rewarding and never feels frustrating. 


I would have liked a fast-forward ability but aside from that, geoDefense is one of the best tower defense games on the iPhone