Avatar: The Last Airbender's most interesting mechanics would have to be the skill tree system and the way the different equipment you find affects your character's various attributes. By no means are either of these features unique to
Avatar, but they both have a huge impact on the feel of the game and the overall gameplay.
First the skill tree. Like I explained before, each character has a series of moves that he or she can and will learn throughout the course of the game. For the most part, a skill can't be learned until its previous, lesser version has been mastered. As your team levels up, the members are each given points and these points are automatically allocated when they are handed out. All skills take three points to master, but while most can be mastered in stages (i.e. Level 1, Level 2 and Level 3), some require all three points to be applied at once. These are typically the most effective moves of a particular category (like Aang's Hurricane attack).
But, while these points are allocated and assigned automatically at the time of leveling up, you can go in and remove points and redistribute them among other techniques. For instance, I found that I rarely used Aang's distraction techniques, or Katara's defensive moves. So when a point was assigned to one of these lesser used categories, I would move it to a move that I used more frequently, typically the offensive ones. This allowed my characters to master the techniques that I used more often quicker.
The other mechanic I mentioned was equipment and how the equipped items affect your characters' various attributes. Each character has seven different attributes. These are Health, Chi, Armor, Life, Focus, Agility and Strength. Each of these determines everything from how effective their attacks are, how quickly they regain Chi, how much Chi they have, how much damage they can withstand, and how much health they have. Throughout the game, enemies will drop tons of equipment, and what they don't drop can be bought or crafted in villages. The different types of equipment modify one or more of these attributes and different combinations of equipment will give different levels of strengths or weaknesses. The six types of equipments are headbands, robes, boots, necklaces, charms and rings.
Though the game doesn't really bring anything new to video games, what it puts together is a fun package that will cause you to lose unknown hours (I know it has for me). Fans of the show should jump on this game because it has pretty much everything you could want and, if you have never seen the series but like Action/RPGs, then at least rent the game, because you will probably fall in love with it too.