Classcraft is a website that teachers can use to "gamify" their classroom content and behavior expectations. The design of the website is based on concepts from fantasy games and literature with character classes such as mage, healer, and warrior. Students get to choose which type of character they will have and what that character looks like. They are rewarded by their teacher for making progress or demonstrating good behavior with experience points (XP). Adding XP allows students to level up, and leveling up unlocks various powers and abilities for their character. Students can also lose health points (HP) for not following behavior expectations. If a student loses all of his or her HP then there is a consequence assigned (chosen at random from a per-made list that can be customized by the teacher).
The site fosters collaboration between classmates that are placed on a team together. Different characters have different abilities and all members of a team are more successful if they work together. For example, the healer class of character can replenish the health points of teammates who have lost HP. Each class has a collaborative power that compliments the team in different ways.
I my experience there are two aspects of Classcraft that get students excited for the game. Students like that they can customize their character's look by unlocking different outfits and accessories. But what seems to excite students most are the real world powers that they can unlock in classcraft. These are abilities earned through the game that allow them to do something in the physical classroom such as take a two minute break, get a hint on a test question, or listen to music while they work. These powers are completely customizable, and will need to be tailored toward each teacher and school's expectations and preferences.
The service is free, but there is a paid option that gives teachers more control. There are some nice features in the premium version, such as quests and volume meter, but the free version has the basics of what you need to gamify your class.
Classcraft is most likely to be successful in your classroom if you use it consistently and allow students to interact with it on a regular basis. The more inconsistently you reward students with XP, or discourage negative behavior with loss of HP, the less effective the site is. The site could be used with any age, but seems geared more toward middle school and early high school. Younger students might find the multiple point categories confusing, while older students might find the premise childish.