How do you incentivize coming to class without making it so students can pass the class only by attending class?
Careful thought needs to be put in to the point values you give to learning experiences in a gameful course. You will want to make sure that assignments and assessments carry the weight they need to (i.e. have high enough point values) in order to accurately reflect the effort students are putting into them relative to other point earning opportunities. It is also critical when thinking about gameful courses (or even more traditional courses), points are not the only motivational lever instructors have for inspiring students to engage in the course.
A philosophical question an instructor can ask themselves about their attendance policies/points include is, “Why is it important for students to attend class?” If it is because you want your course to be a learning community where everyone is actively engaged, then you will want to structure your class sessions to motivate those interactions (and, in turn, attendance). If it is important for students to attend class because they will be getting opportunities to practice the skills you want them to learn, then structuring your grading scheme and class sessions to encourage participation in those activities is another way to leverage.