Have you considered selling this as an assessment tool? You'd probably have to drop the Kung-fu theme but that doesn't mean it would have to be boring either.

Have you considered selling this as an assessment tool? You'd probably have to drop the Kung-fu theme but that doesn't mean it would have to be boring either. I think a scored and timed test would be really useful to HR departments at large corporations who need to screen technical applicants. One hitch is that with most thing *nix, TMTOWTDI. Do you check for the result or do you check the command typed? Just as an example, your screenshots show the pushd/popd lesson. If prompted to change to my home directory in under two seconds I'd just type 'cd'. To get back to where I used to be I'd type 'cd -'. I never use pushd/popd. If the lesson is presented as 'use pushd and popd to navigate the filesystem' then there's no issue.