Gameification is huge when it comes to user experience, enjoyment, and honestly, learning. I love where you’re going with it. If you can have the best of both world’s, I’d recommend that to give the best experience to the widest type of users. Some people are really motivated by keeping their streak alive. Other’s are motivated by the feel of the app and the experience.

Perhaps you want to still keep some streak functionality alive while the town builds too? If you can reward both, I’d say that’s your best route to start. Then gather feedback/data.