Happy Wars is a multiplayer online game, defined as a role-playing strategy game, although it also has a short story-driven single player campaign mode. The multiplayer mode consists of two teams of up to 15 players attempting to destroy the other team's castle while also defending their own.
The players choose from one of three classes: the warrior, the mage, and the cleric. There are also subclasses, although the only ones implemented at the moment is the Warrior-type Berserker as well as the Mage-type Zephyr and the Cleric-type Engineer. Each class has a base attack and other unique abilities that are available as the player gains new levels. Each class also has a unique "Team Skill", where players can gather teammates together to allow the casting player to use more powerful skills. The more players that aid in the use of the team skill, the more powerful the ability becomes.
The game also has items that can be purchased either through playing the game or through microtransactions that allow in-game items to be purchased with Microsoft Points. There are items in Happy Wars that can only be purchased with Microsoft Points. They are usually powerful items that can allow you to get a head start in the game. The developers have announced plans to release new maps and items "every 1-2 months"