To make sure your dog enjoys the game start off by hiding the toy out in the open in easily accessible places. Once they get the hang of it start hiding it in more and more challenging places. Also keep in mind the colour of your toy, a blue toy on a blue rug may not be visible to them, eventually they should be able to use their nose to find the toy but to start with make it fun and positive.
You'll notice that Kobi is a bit vocal when he plays tug, he just like to hear himself and sound tough. The first time was a nice easy spot for him to find it, the second time was more challenging and he had to use his nose to find it.