Commander Keen Level Maps
I spent so many hours playing the first game as a kid, decoding the alphabet (which I would later discover it tells you how to read in episode 2 or 3 anyway), trying to get every last item, etc.My favourite bit was the dark, fiery secret tunnel underneath one of the larger levels (http://www.commander-keen.com/levelmaps/1/013.gif), which teleports you to the city on the right-hand side of the world map at the bottom of the level maps page, not really visible from the map screen when going between the main cities... but I no longer remember which of these maps is that city, alas(or maybe not alas: I hope I've put some more currently useful information in that part of my brain instead. Thanks for the nostalgia!)