Difficulty Level 3 With 24 hidden treat compartments, the Nina Ottosson Challenge Slider dog treat puzzle is one of our most challenging puzzles yet! Nina Ottosson treat puzzle games are a great way to engage your dog's mind with challenging and rewarding activity. The Challenge Slider will keep your dogs mind busy with 24 treat compartments. In this game dogs must move each slider, one at a time, in different directions, to reveal hidden treats or food. Slide, treat, and repeat