I remember having to do a similar compiler assignment in C in college. I think that it was the key assignment for making students believe that programming is absolute drudgery and in no way fun. It was the culmination of the semester, and considering how hard many of the students were working, there was frustration that this was all they could make after a semester. I think that your plan will not go well, and could quite possibly sour your students on programming for life. If you teach the text game first, though, that would make a world of difference.