I occasionally will use treats or kibble to play games with my dogs. One of the games I like to play is having them use a treat puzzle. It is interesting to see the different methods each do uses to get at the treats.
This particular puzzle both has removable pieces (the white bones) and sliding doors. It means that the dogs have to use different skills or methods to get to all the treats hidden in it.
The instructions say to use treats in all the slots at first, then go down to only putting treats in a few of them. I still load it up and put at least a few treats or kibbles in each slot.
I think this puzzle is a great way to entertain the dogs for a little while, and I find it even works for entertaining guests watching the dogs try to get at the treats.