NO REMOVABLE PARTS: This dog game has built in play pieces that don’t come out when your dog plays with it. TWIST IT: Unique to the Nina Ottosson Dog Casino dog game are the locking bone pieces. If your dog is good at solving puzzles, introduce them to a new challenge by simply twisting the bones on top to lock the drawers. LEVEL 3 CHALLENGE: Nina Ottosson Dog Games and puzzles are great for dogs of all ages, breeds and sizes. This level 3 dog game is especially recommended for more challenging play, but can be used with dogs of all play levels.