This offer is for the Gold members only who can download the game for free this fall. Microsoft however, has yet to announce how much the Silver members will have to pay in order to play the game.
Happy Wars has support for up to 30 players at a time who can brawl in a 15 vs 15 match for some serious cel-shaded action.
Players can choose between three classes: Warrior (is handy with swords), Mage (can breath fire) and Cleric. In addition the game also hosts an offline mode that comes complete with a campaign full of solo missions.
Here is an announcement trailer for Happy Wars.