Apart from rewarding Tjido for coming to us when called (as well as when he comes on his own) we have started doing the following games (I decided to give them fun names):
Sniffing the Leaves Game!
You put some leaves together in a smile pile and throw treats in it. Meanwhile dog has to wait.
Then he can sniff them out!
What's on the Tree?
Push some treats on the bark of the tree, so they stay put. Ask your dog to find them!
The classic "come" game
If you are outside with another person you can play the come game, where you stand in front of eacht other asking the dog to come (he gets a treat) and getting further apart every time.
Why not train with your dog in a challenging environment?
These are nice ways to give treats in a playful manner. Especially the first two games are very good because your dog needs some self control when waiting and the sniffing is great as mental exercise!
If you have more ideas leave a comment! :D
PS: Funny story! We have a strange population of parrots in Amsterdam (.. yeah the green tropical ones) and they have migrated to our small park area. Man they are aggressive! Every time they see Tjido they attack us! And well, this icelandic sheepdog just stares. I thought he would go ballistic but he's like "hey guys, what are we playing at?" haha I made a video so I'll post that later!