This game is amazing, perhaps it can be a bit much with jsut the 3 levels (despite multiple paths) but it really shines when you play with other people (or without the reticule if you've played it too many damn times) ... Level 62 for me so far...
CD/Game Exchange in Silver Spring and College Park (if you're out that way)
like the one in Rockville are usually good treasure hunting.
there are 2 more in DC, but I've only been to one (was a pain to get to)