I love this one
MC is forced playing a real-life game with other kidnapped teens, all specialized in a specific type of game. They have to team together to clear the different games send by a "Sensei" with a llama mask, while gaining enough view to clear the stage.
Super cute art (It's a shoujo with lots of action), refreshing plot, appealing character.
Naka no Hito Genome [Jikkyouchuu]