Since 2006 I've been teaching an undergrad general education (i.e., for non-scientists) course in Computer Science called Computer Games at UNSW@ADFA (University of New South Wales, at the Australian Defence Force Academy) that has used a levelling metaphor. Students start out as "Newbs" (Fail level) and level up through Knave (Pass Conceded), Squire (Pass), Courtier (Credit), Peer (Distinction) and L33t (High Distinction). A large pool of elective tasks are made available to the students. These fall into one of three categories - Delves, Quests, and Odysseys based on their difficulty and work involved. Students undertake whatever tasks they desire (within a few constraints) and will level-up on successful completion of a certain task mix. Each student has their own Wiki where they record their progress on tasks and where I and my markers provide feedback on their progress. Think of it like a Quest Log. Heck, there's even a series of weekly exercises which might be considered the "main storyline" of the course/game, and there's icons for each of the ranks and quests. The 2009 version of the course can be found at http://seit.unsw.adfa.edu.au/coursework/ZGEN2301/index.html, with task lists etc. Student Wiki pages are there also but password locked (plagiarism issues), otherwise you'd be able to seem the excellent work that (some of) the students have done.

I teach a Computer Games course for non-science students. That is ones possessing no programming skills, but quite familiar with office tools like Word, Excel, etc. This is a perfect application to expose them to some of the details of whats happening mathematically without frightening them off with code or too many formulae (they can play with the numbers).