This is for the paid version of Robo Defense. Which is one of the first games I downloaded for my Sprint HTC Hero. This game is very addciting, with multiple maps and endless levels, the fun doesn't stop due to the variety and challenge each map presents. The level difficulty increases as you go, but don't worry, you have a nice array of weaponry to fend off these nasty robots. You can use a gun tower, rocket tower, and a slowing tower to start. And after upgrading, you can get a missile launcher, anti aircraft tower, landmines, a flame thrower, mortar turrets, and a teleporter. To add to the replayablility of the game, there are a variety of achievements you can earn, such as completing the map using only gun towers, or only missile turrets. This game never gets old, you can try different layouts each time you play, and the different maps with the different entry/end points presents quite a challenge for a long time to come. Definitely worth trying the free version, and if you like it, purchasing the full version.