Are you up for a challenge.  If so then see if you can get through the 13 very difficult missions in the Battle for Alandria tower defense game.  Each mission consists of several rounds and each round is divided into two parts.  You buy, build and upgrade your army during the first part of the game.  The second part of the game is a battle in which you can control your troop units.  You hero ears experience for each level and when he reaches a new level he gets even more improvement points that you can use to improve your hero.