Robo Defense is the ultimate portable tower defense experience.  Featuring open maps, upgrades, achievements and nice graphics. 

 The full version features 5 maps with unlimited upgrades and difficulty levels. 

 A free version is also available (try it first!). 

 Free version progress is automatically imported into the full version, should you choose to upgrade. 

HTC Desire, San Francisco: Turning off "High Quality Graphics" fixes known issues.

Galaxy S: Turn on "16-bit Backgrounds" to fix studdering performance issues.

Atrix: Disable sound to improve stability

 Performance tips: If the game is running sluggishly, try playing fully  "zoomed in".  Turning off "High Quality Graphics Mode", in the options menu, will also help on some phone models. 

 http://lupislabs.blogspot.com

Robo Defense is the ultimate portable tower defense experience.