You talk about the levels contributed by your community - will there be / is there a way for those to be shared under open licenses too?
Hopefully we can keep all levels free for everyone anyway, since recruiting is looking pretty good as a monetization strategy so far.
After someone takes a job through CodeCombat, the employer would pay them some sort of referral fee. This sort of arrangement is common; a typical fee structure is around 20% of the new hire's annual salary.
Employers get a concrete way to assess the skill of potential employees, job-seekers get free visibility they wouldn't otherwise get (this sort of thing tends to benefit newer programmers whose limited experience doesn't accurately represent their raw skill and potential), and CodeCombat gets paid. Everybody wins.