Before you ask, yes, this is another tower defense game, but this one is actually unique enough to merit a mention. Where most tower defense games opt for a linear upgrade path for a set of towers, all purchased from money accumulated by killing enemies, Epic Defense uses a less linear and more experimental approach.
Instead of having an array of towers you can purchase for various prices, you're given a set of blank, featureless towers. Each basic tower has no weapons of its own, but is granted unique abilities by adding three gems to the tower. You have a bank of red, yellow, and blue gems.