You can turn the Offered Attention Game into a game where you reward puppy for following you. Warm up with the Offered Attention Game. Once he is looking back quickly, instead of just clicking and rewarding puppy for looking at you, move away and click and reward puppy for following you. At first, puppy is more likely to follow you if you are walking backwards.
To keep it an exciting and active game, click while puppy is following you (rather than after he has caught up). Toss a treat, and as soon as puppy looks back to you, start moving again. Repeat!
Once puppy is really good at this game, have puppy follow you for more steps to earn reward. And when he is truly an expert, you can play this game in new environments and with more distractions. Remember to add more steps and more distractions gradually so puppy has a good chance of being successful.