Course gamification: rewards that aren't bonus marks? I am experimenting with a game mechanism in my course in which students can progress through 4 core competencies, A, B, C, and D.  Each competency has 3 levels, 1, 2, and 3.  The game component is optional.  The idea is that each level of each competency will be linked to a few homework activities that, once completed, achieves the level.  When all levels are achieved for a given competency, the competency itself is achieved.

In my department, homework assignments are not graded (projects and so forth are, but I can't assign a few questions for grading).  As a result, I want to ensure that my students are actually going to do the homework I've assigned.  I can give bonus marks. 

I'd like to give rewards for completing these competencies, but I don't want the course so overloaded with bonus marks that students can too easily get 100% without doing well on the final/midterm/projects.  So far, the ideas I have are:


Complete level 1 for any competency - earn 1 grace day for handing in an assignment late without penalty
Complete level 1 for all competencies - earn 5 grace days, in addition to the 1 you gain for doing the above
Complete all levels for any competency - bonus quizzes now worth 7% (originally they were worth 5%)
Complete all competencies - 2% course bonus


I'm not a big fan of all of this bonus, but other than bonus marks and late days I'm not sure what other options I have.  Any ideas?
One idea is to include some problems/tasks in the final exam related to those competencies. This might not be possible.

A student who achieved the highest level in that competency automatically gets full grade on that question, and doesn't have to solve it (thus getting extra time for the rest of the exam). 

For levels 1 and 2 you can award free part marks, and the student gets either the free marks or his grade on the problem (whichever which is larger).

Added 

Depending on how long/short it needs to be, something like below might work (or could be terrible):

Exam:

Part A (short questions testing the competency parts)

Question 1 (competency A): bla bla bla

Question 2 (competency B): bla bla bla

Question 3 (competency C): bla bla bla

Question 4 (competency D): bla bla bla

Part B Actual exam, Questions 5- ...