Read this article about one presumably successful effort. [npr.org] And let's look at the assumptions these efforts make, and their solutions.
What bothers me about the article is how little they talk about actually enjoying computer science. They talk about editing Darth Vader's voice, or having all the answers to a quiz be 42, but......what about the actual subject? If you don't enjoy it, maybe you should go to a different field. Because I can tell you, once you've graduated, the real world isn't going to be gamified.